There is some gutter loss, the amount depends on the type of binding used and what you're binding. For example, if you bind older comics that aren't full bleed (thus having a built-in gutter) you won't lose anything no matter what method you use, typically. But newer comics if you bind them oversewn, or even DFAB, will have some gutter loss. Smythe sewn will have less gutter loss, but you can't use trades or remove any pages from the floppies.
As for the number of issues, gosh, I dunno. I have about 150 or so binds; some have as few as 10-12 issues, others as many as 40 issues. It's a lot, regardless