Since this is my first post here, hello everybody! Be warned, it is a long list of questions!

I'm going on a road trip with my car in two weeks and I have a couple of questions about my route.
I'll be going through Slovenia -> Hungary -> Ukraine -> Belarus -> Russia(Saint Petersburg) and then back.

I'm still unsure on which route to take on my way back and it's basically up to border crossings. Unfortunately I don't have plenty of time to waste, at least on the days I have booked as driving or transit days, so being stuck at the border for hours is something I would like to avoid at all costs.

Does anybody have any ideas which ones to take and where? I'm guessing the lines at Hungary -> Ukraine might be a bit long, does anybody know? I'm planning to cross at Luzhanka/Beregsurányi, I'm hoping it's not a 6 hour cross.

Where could I find a website with border crossing waiting times for any of the countries mentioned? So far the only reliable source I've found is for Finland which has everything sorted, but it's my least probable route of return.
Can anybody point me into the right direction for traffic information websites?

Next up, going from Ukraine to Belarus. The route here splits, I'll be starting in Kiev and going to Minsk, Via Michelin would like to take me east(Kiev -> Skytok(crossing) -> Babruysk -> Minsk), while google maps would like to take me west(Kiev -> Aliaksandraŭka(crossing) -> Mazyr -> Babruysk -> Minsk). I'm liking the Via Michelin route more, because it seems like a far better route and possibly roads.
Going this way it seems I'll be crossing at Skytok(I believe) and would like to know if this is optimal and the least waiting times or is there a local smaller border crossing I can take?
Next time is going from Minsk to Pskov(I don't intend to drive more than 300 miles and 7-8 hours per day, so this is an overnight spot), Gmaps would again like me to take some weird route that takes me over a border crossing that doesn't even look manned 24/7(Minsk -> Polack -> Doloscy(Crossing) -> Pskov) Via Michelin again has, what looks like the better option, taking me from Minsk -> Orsha -> Vitsebsk -> Lobok/Crossing -> Pskov.
Again, is this the better option? Where could one find out about waiting times on the border for Belarus? Or just general traffic information.

Now the final stretch where I have the biggest doubts and variatons is leaving Russia. I'll be starting in St. Petersburg and going back home on a Friday, I'll have three full days to drive somewhere in the region of 2300 kilometers. It seems possible in 72 hours, but it will be constant driving through all the hours of daylight.
And here's where it gets tricky, since time is not on my side I have canceled out what I wanted to do first, go from St. Petersburg -> Narva -> Tallinn and then down. From what I've read you can easily spend a day waiting at the Narva border crossing so I've ditched it altogether. My heart would like to at least drive through Tallinn, but it might be a slim chance. I've narrowed it down to these three options:
1. The most logical direct route: St. Petersburg -> Pskov -> Ubylinka/Grebņova(crossing) and then back home in the borderless vastness of the EU. This seems like the most logical and fastest route, taking me down the same road I came up, but completely cutting out Estonia and most of Latvia, getting rid of my chance to at least see Riga.
2. The slightly longer crossing to Riga: St. Petersburg -> Pskov -> Sumilkino/Luta(crossing) -> Riga and then back home in the borderless vastness of the EU.
I'm slightly preferring this option, even though it seems like a bit of a detour. But it depends on the waiting times at the border, reasonable, fast?
Would love to at least see Riga quickly.
3. The last option is the one that requires the most "planning" and money and this is going through Finland and taking a ferry to Tallinn.
So the route would go St. Petersburg -> Vaalimaa(crossing) -> Helsinki -> Tallinn w/ ferry. Since this would require booking a ferry it would also severely reduce my time flexibility with border crossings.
Is this is a quick route for border crossings? It is the longest and in a way slowest, depending on other border crossings, but from what I've read Narva is by far the slowest and worst option. It'd be great to very briefly visit Helsinki and Tallinn, but if the other two border crossings turn out to be far faster, I'll probably have to take them in order to be home by Sunday night and at work on Monday.

As I've mentioned, any local websites with border crossing times would be great, so I could at least reasonably predict my arrival times at my hosts.

Next up, visas! I'm from Slovenia and I've got the Russian visa covered, putting all the paper work forward tomorrow, but the Belarus visa is a little bit more tricky. Since there's no consulate or any sort of representation of Belarus in Slovenia I'm going to have get mine in Budapest. The problem is I only took one day off for it, so I'm going to be a bit on the edge. I'm going to do my best to get all the paperwork right and be in touch with the consulate before I get there, pay the express fee and hope to get it done on the same day. I've heard people had good experiences with the embassy in Budapest and I'm counting on that to get it done the same day, otherwise...well things might get interesting on the road.
Can anybody confirm or deny this by any chance? I'm hoping to put the paperwork on the counter first thing at 9 am when they open.

As for the more part...well any information on the conditions of the roads would be most welcome! I have no clue what to expect, I've heard to road going to Lviv is rather bad. Anything else? Dos and do nots?

Thanks for all the help and reading through this pile of text!