Hi, peace upon you too.
Well to start off with,
Name? Doesn't really matters to me.
Location? Yup, seconded your idea as the major concern is noise-pollution & accessibility.
Opening hours? Cool!
How many studios? $ would be IDEAL but let's jz do w/o the recording facilities first & see how it goes.
How big each room? I don't really know how big is a 300sqft but importantly is, not too big, especially those factories's sites with high ceilings, as I find the sound produced is less compact, you know what I mean but too small also can be restrictive. As long as it can house a couple of plastic-chairs to sit & not neck-to-neck for the guitarists, should suffice!
How much to charge? Well, it depends on the equipments provided & most importantly your operating cost needs!!! Kids or people in general nowadays I find it that they really have the spending power unlike my days in the late 80s, schooldays, where pocket $ is so limited. S$20/hr sounds reasonable but then again your equipments must be justifiable.
Equipment? Well, you can get great bargains from SOFT buy/sell sections as well, no worries. I don't think you would want to get smething brandnew, right? That would certainly be a blow-off to your budget!! I think all you need is amps & drums' sets..Hahaha...
Accoustics/Sound insulation? Yes, of course a good sound-insulations contributes to the compactness/quality of the jamming! This, you have to really invest, to make it simple!
Do we need a lounge for jammers to hang around or 'lepak' before of after jamming? Not really but the best is to have a Teh-tarek & roti prata stalls nearby your studios. That way, you'll save $ & xtra housekeeping (can drinks/bottles contributes to the hygiene of the place) on these lounges you have in mind.
Do I need to advertise the new studio? Yes, of course, especially when yours is new in town but don't worry much as words of mouth goes around really fast if yours is a reliable ones, trust me! Maybe get the bands to recommend their friends & give discounts to those who did the recommendations, stuffs like that..
How about setting up a KTV/Pub kind of setup? That would be of secondary importance. Wow, you really think this far, man...Upz to you!
Last but not least, all the best & hope to try out your studios!
Peace upon you!
Best regards,
Ang3L