"Does it work well": For many extremely (some have never had any issues at all), for others less so (see for example fMMS causing trouble), YMMV. Trying is free though (unlike with Joiku, which also is rather YMMV from what I have heard)

The custom kernel required is titans kernel (though the dependencies are specified in such way that any other properly packaged kernel with correct modules can fulfill them), if you're rolling your own (kernel) then you already should know enough to 1. compile it with correct modules 2. package it properly or install/run MH (MobileHotspot) without using the package.

fMMS issues is something I cannot comment on, AFAIUnderstand it messes about with the packet data settings somehow: if that causes you trouble with MH then you need to figure out how to solve it and preferably make a patch I can include in the official packages (I do not have the time or interest to debug this issue).

Wiki page: it would be nice if someone else (tm) could make one.

"I don't have the time...": I will be very disinclined to reply to the same questions over and over and over again, a little self-help goes a long way.

"No connection for laptop/whatever but backend starts fine": I have seen this sometimes but not in a while (which makes investigation kinda hard), debugging this is same as debugging networking in general (since MH really doesn't do anything special it just automates a bunch of things you could do from the UI/terminal yourself), as for network debugging aside from the first checks (pings with manual IPs, arp resolution test) there isn't much someone who doesn't know how to debug networks already can do (because next steps involve using packet sniffers, network scanners, low-level wifi sniffing tools etc and I will not be holding anyones hand through those procedures).

"Device X needs dhcp refresh": This is a problem in device Xs end (it probably treats Ad-Hoc connections as special).

"Does not wait long enough": Known issue (the wait time is hard-coded due to various complexities in receiving the actual "connection is now up" -signals), unlikely to be fixed by me though (it's a minor annoyance easily worked around and fixing it in a clean way is complex)

"Mobile provider vs tethering": There are ways to detect that someone doing NAT and sharing the connection (on TCP/IP level, no need to reconstruct the HTTP [or other protocol level] request and analyze that), doing this on a large scale is expensive though so it's quite unlikely that you will get detected (supposing your provider forbids tethering and/or connection sharing). This has nothing to do with how much you pay for your traffic in general (for example some "flat rate" subscriptions only include for example 3GB of traffic and after that it's billed per megabyte [not quite "unlimited"]).

Infrastructure mode: not going to happen (as stated on the first page: it's almost impossible [and only almost because very few things are actually impossible: usually it's "just" not worth the expense/trouble])