Very basic (off to work in few mins)...
Kuhlis do much better in big groups of 10+, far more likely to see them out and about. Anything from a 45cm long tank will be fine (but bigger tanks give us longer to realise things are going bad, the greater volume of water gives more stability).
Pakistanis need 4-foot long tanks, quite social, so 5+ group ideally.
Clown Loaches reach upto ~30cm, are very social, do much better in big groups to form complex hierachy (at least 6, but more the better). Need 6-foot tank. Prone to ich, very sensitive to water quality changes.
Dojo/Weather Loaches are sub-tropical, best kept at 18-22C, very social and do well in big groups (at least 6). Should reach close to 30cm, despite their inactivity burrowing in soft sand during the day in shady areas, they are very active at night and can be found doing laps of the tank midwater.