Checking valves and shimming - lots of Q's - need A's
 

I presume if the valves need shimming the cams have to come out? Once I find out what shims I need (if), will a Suzuki dealer usually have them in stock? Are they common parts across the range or indeed across manufacturers?

Any other advice or gotchas?

Yes, if the valve clearances are off the cams will need to come out to get to the shims, (they're under the buckets), but unless you have a load of miles up I don't think you'll need to adjust the valves, I have checked the clearances on several SV's, including one with 75,000 on it and they never need doing, which was nice.
If you need shims Suzuki dealers hold some stocks, if you're lucky they'll let you swap yours for the ones you need, (plus a consideration most likely), rather than have to buy new ones.
As I've not actually had to remove any I don't know what size, (diameter silly), shims they are, but I'd be surprised if they only fit the SV, I don't know of any manufacturer who does that, (but if there is one that does it will be H&^%$).
In the manuals it will tell you to remove the rad to check the shims, as it's likely you won't need to actually adjust them, this just adds to a job you might find out you didn't need to do, and you can check them if your careful without removing the rad, which I'd only do if the shims did need changing.

Thanks for that: I'm almost tempted to not bother checking.

I'd still check them, it's easy enough, just don't take the rad off as it would be annoying to have done that for nothing.