I have 8 plants going in a 4x8 I wouldn't want anything smaller / realistically I should of had twice that space with what I wanted to do LST wise.
So with that
32 square feet for 8 plants X (3) to accommodate your 25ish plants = 12 x 24 space
64 square feet for 8 plants X (3) to accommodate your 25ish plants = 24 x 48 space
that would be my recommendation, In terms of light I use 2 1000 watts per 4x8 if we use 600's instead you would still need a minimum of 6 lights but ideally I would say 12
12 x 24 foot = 6 lights 1 for every 4x4 with some overlap
24 x 48 foot = 12 lights 1 for ever 4x4 with some over lap
You can obviously get away with a lot less but that would be my ideal recommendation for big plants with big yields but it also comes with big cost for electricity, bare minimum that's 3600 watts just in lights. not to mention inline fans, dedicated AC unit, ect. So unless you have a decent amount of growing experience that is a huge financial investment / risk that could be a flop with one wrong feeding, hermie mishap, bug problem, PM issue ect ect.
Long story short good luck with your grow and if you have more questions I am more then happy to help answer them. here is my current flower room for size comparison 8x4
Day 1 of Flower
Day 25 of Flower
Day 1 of Flower
Day 25 of Flower