That is a good score! But now you've got to buy the mid pipe! I've a 040 pipe sitting here I've never mounted ... been waiting years for a good deal on a mid pipe ... about $225 usd. The Ti pipe is a beauty and saves about 1.5 to 2.0 kgs., sounds NICE, no repacking, will never wear out or rust.
If you buy a new Corbin, they will get you the proper seat to fit your tank, so yes, tank first .. and the big Acerbis looks better than my old IMS. If you buy used, just check with seller on fitment.

Most seats you find will fit your Acerbis 6.6. But check to make sure before buying. Lots of seat options. I like my Corbin but many brands out there.

Hard vs. soft bags argument goes back and forth here ... TONS written on this. Up to you. I've used both and now prefer soft panniers as I lost about 35 lbs. going from hard bags to soft panniers. So for me it's about weight. My Nelson-Rigg bags pack up easy ... I use inner bags. No idea on racks in UK, but many options on internet, Pro Cycle and more. Since I use throw over bags my racks are very light weight, don't have to support full weight of bags ... the seat takes most of load. Racks were less than $100.

Once you discover ProCycle you'll be spending a lot. Even with shipping it's cheaper to buy there than UK or EU. (mostly) True one stop shopping.

You can start a blog here on HUBB or just start a thread in the Suzuki section here. I have a very old one there ... I've learned TONS more about the bike since then.

There was some question about delays with the Bridge motos guys ... when do you expect to get your bike? Ship containers can have long, unexplained delays. Good luck, hope it shows up soon!