Bike sounds neglected. Has it been idle for a long time? Outside of the water pump and the oil seal the stuff on the list is fairly easy, just time consuming. You did say you had all winter. Following are my first impressions:
Intake boots are not impossible to change, just time consuming. Lots of discussions on that job here and on the net.
Air filter, How many miles on your bike? They are good for 50-60,000 miles or more unless a mouse has been living in there.
Water pump, lots of experience here by the inmates. Lots of advice available.
Oil leaks. Get some gasket in a tube.
Valves and cam chain guides. Look at guides when you go after the oil leaks. Valves, easy to check, lots of experience here.
How old is final drive oil? Change it.
Main seal leak may just be the clutch o-ring. You need to pull the transmission and take apart a lot of the rear of the bike. Not a bad job, just time consuming. Gives you a chance to check the clutch friction disc for oil contamination and lube the splines.
Front brake pads are easy to change. I use generic kevlar/organic pads I get on eBay.
Cables. Probably time to replace the clutch cable anyway.
Brake bleed is an easy job and should be done every two years. Then see what codes the ABS has.
Replace the rear master cylinder with a Chicom unit from eBay. Not a big job and the master cylinder is under 20 bucks. There is a good thread here that covers the job.
Side stand bushing is another easy job that doesn't cost a lot for parts. I did mine and it didn't change anything.
Seat latch probably isn't a very big job. depends on what is loose. Does it open and latch easily?