I probably would have put this in the Certification forum..
Which you may want to browse anyway. I'm certain some of your questions have been asked before..
Personally I prefer non-vendor specific certifications such as LPIC, over vendor certifications such as the ones from Suse or Redhat. I've been burned by Vendor certs before *cough* Microsoft *cough*
it left a very sour taste in my mouth not to mention my wallet. (also gave me a push to start working with Linux)
I'm certain there are people here that will say don't waste time with LPIC, RH is the only way to go. That is a decision that I feel is a personal one, that you will have to make for yourself.
Although there are times when vendor based certs would be of more value, it would depend on the situation and job requirements involved. LPIC is also a lot easier on the wallet than the RH and Suse certs..
So anyway theres my opinion and two other Linux Certs for you too look at.