If you are not sure you can dedicate long years to your fish, buy a smaller school, easier to perhaps move from tank to tank, place to place...In 6 years, mine went through 3 different tanks......
I bought my first group of 5 nearly 6 years ago and since then I upped their number to 13.
Besides what's being said, my advise is to start doing daily or every other day partial water changes on the quarantine tank.......and try keeping it up for a couple of months if you can.
Small clown loaches come underfed/malnourished, skinny and perhaps carrying worms and parasites, but if they go into a tank with pristine water and high quality food, they'll all make it. Its a good idea to de-worm them all now as previously suggested but to be honest, mine were not de-wormed for the first 4 or so years I had them.....
Having said that, I did buy a loach last year that wouldn't have made it if he wasn't de-wormed...The signs for parasites/worms are always the same, skinny and pinched above the eyes although eating...Healthy clowns don't tend to develop this. It may take 2-3 months for the conditions to develop....if not already visible, hence quarantine.....
Besides that, a well filtered tank, high quality food and weekly large water changes, and you won't have any issues with your clowns.....They aren't any harder to keep than any other average fish. I also have denison barbs with mine by the way. They don't bother each other and the denison barbs are really good dithers for clown loaches as they're active and don't spook easily, plus they don't tend to eat from the bottom.
Good luck.