"How can I prevent any health complications from a recent root canal treatment?"
Build up your immune system, do oil pulling (see recent thread here on OP and root canals), and relax!
I sometimes think all the negative talk about root canals here at curezone is worse for our health then the RC's themselves. Fear is the killer!
"Besides removing the tooth, what alternatives are there to root canal treatments?"
The alternative is to refuse the RC. I did that a couple of times and the teeth were OK! But sometimes a RC can mean keeping the tooth. In that case I personally think it is warranted.
"Is there any way to regrow the receding Papila ( gums between the teeth)?"
Oil pulling is excellent for gums. I think some have seen regrowth. CoQ10 or (better) ubiquinol, folic acid (a B vitamin), greens, and vitamin C could help.
"Will we ever be able to regrow our teeth?"
I believe so. In fact, if we had enough faith, we could probably do it now.
"Besides the monetary loss, why do dentists refuse to entertain any belief that their treatments are harmful to their patients health?"
I think most of them really don't believe that they are harmful. It's about paradigms. They are in a certain paradigm in which conventional dentistry makes sense. But there are holistic dentists around if you look for them.
"In addition to brushing and flossing, what is the best natural/healthy programme to maintain oral health?"
Nutrition is the most important factor. Brushing and flossing is secondary. If nutrition is excellent, brushing isn't even necessary! Check out Ramiel Nagel's work: http://www.curetoothdecay.com/