Even if it might only cover a part of your question: Don't let you scare by those "virus" marketing bluff. There is no such thing as a virus on Android, and hardly will be.
Sure some companies want to sell you their "anti virus product". But if you take a deeper look at what it really does (apart from the marketing buzzwords), none of them seems to really deal with viruses (how should they, if there are none?).
So what's the thing behind it?
Mixing of terms. Today far to many people taking "virus" as the "master-term" including all kinds of malware: virii themselves, trojans, and other evil doers. The Wikipedia article on the term "computer virus" starts right away with the most important fact:
A computer virus is a computer program that can replicate itself and spread from one computer to another.
Ever heard of such a thing on Android? No, here the user has to explicitly install it, and agree to its requested permissions. So how should this spread itself? (Malicious gossip has it these terms apply to the Windows OS and most of its payed programs: they replicate and spread from computer to computer via file sharing...). So Wikipedia continues:
The term "virus" is also commonly, but erroneously, used to refer to other types of malware, including but not limited to adware and spyware programs that do not have a reproductive ability.
There you go: You don't have a virus.