The shorter duration of antibiotic course the better. It's good to use some topical retinoid when you use oral antibiotics. Topical retinoid can cause breakouts but it will help to maintain remission, when antibiotics works only when you take them. Include topical retinoid as fast as you can, and after few weeks stop using oral antibiotic and start including topical BP. Topical BP + topical retinoid should be sufficient for mild/moderate acne but will not be enough for severe acne. Of course consult it with you derma/GP. It's just my opinion
Have been told by multiple dermatologists that acne rarely permanently goes away on antibiotics unless you continue with BP body wash or topical retinoid treatment. Patients tend to relapse after treatment ends unless they do some sort of maintenance.
The doses and antibiotics used to treat acne are not generally known to cause resistance from what I have read. Unless you're taking a very strong broad spectrum antibiotic, you're not at high risk for C difficile either. You can read up on it on google scholar or pubmed, butthe harms of relatively short term antibiotic use are very minimal. Typically include acute stomach upset, gas, etc. that usually goes away when the antibiotics are stopped. Obviouslythere was rare cases, but your doctor will let you know if you're at risk.