Welcome to the tribe!
If you can handle that 750 turbo, you'll love the 695. These bikes do run lean, you can go broke band-aiding the issue, or just bite the bullet and have the ecu reflashed. As for the seat, check eBay, they pop up for around $100, any one from 01 to 08 are the same. As a 6'0" 230# rider, I can tell you you're correct in the bike being under-sprung, these things are sprung for 160# Itallian teenagers. Go to Race Tech's site and you can plug in your weight and the bikes and get a spring recommendation. I would consider swapping the rear shock for one off a SBK. Both the 748/916 and 749/999 units will work if you relocate the voltage regulator which you should do anyway. If's fully adjustable and can be re-built, the stock unit is cannot.
These things are an absolute hoot when setup correctly. Check out my thread below this one for my build over the last two years. A bunch of the images have been corrupted, but PM me and I can shoot them to you or if you have any questons.