a) There's nothing bad in itself in doing MBA from distance learning (DL), but it is my opinion that it lacks two of the most important things that one gains from Exec MBA/full time: (most importantly) interactivity & networking with the class & professors; the drive to study.
Therefore, I don't see much point in DL MBA (in fact, some cases have sprung up where people were found to be running DL from home without any qualified professors).
On the other hand, if you don't want to leave your present job (which is a very sane decision), it will be very good to go for Executive MBA, which is part time MBA; classes held on the weekend.
b) Doing a PG course in management and then going in for EMBA is redundant and a duplication of efforts.
c) A no. of reputed colleges like IIMs, IITs, IIFT, XLRI, MICA etc. do provide EMBA courses - both at their own campus and through two-way video conferencing. The point about their campus option is fairly obvious, but it is their video-conferencing that takes the cake. Basically they have tie-ups with some third-party (e.g. Hughes, NIIT, Educomp) which sets up their conference through satellites.
Regarding the minimum no. of years of experience required:
It depends on the specific course you want to go in for. The thing about EMBA is that there are many many options depending on your needs. E.g. there's an EMBA in office management that requires 0 experience and EMBA for CEOs that requires 15 years experience...
you get what I mean. So, check your suitability.
Regarding websites with info: http://www.hugheseducation.com/