Media for Router help please

Router help please

I've been using a Linksys BEFSR41 wired router for several years - mostly for it's NAT functions - but every so often, to attach a laptop when someone is visiting.

My family situation is changing and I have to create wireless access - and I would like it as safe as possible - but I don't know anything about doing it. My experience with Linksys has been excellent and therefore, I would tend to stay with their products if possible.

I will have 3 computers using the router. It must cover about 60 feet in an apartment building with thick walls between the rooms. I would very much like to cover about 120 feet (thick walls) and therefore I think I'll need an access point for that?

Questions:

Is one router faster than the other? If so, what specs should I look for to get the fastest possible?

And will one router go greater distances (penetrating walls etc.), than another?

Should I keep my desktop connected to the new router by wire and therefore, keep it better protected while the other two laptops will use it wirelessly?

My desktop has all the peripherals attached (printers, scanner etc.). Is there any way to keep my desktop secured with no printer and file sharing, while have it active on the laptops? Or, can I just turn on printer sharing without turning on file sharing?

As you can probably see by now, I don't know much about this and have always stayed far away from wireless for security reasons - now I must jump into that water.

Of course, answers and recommendations will be greatly appreciated. But also, if there is a particular link which is considered the best source for this information, I'd appreciate the link as well.

TIA

Louise