Hi Grey1
I will try and answer your questions;
1) Should I go thro the agony of helping my wife renew her ESA or should I start a first ever application for PIP for her … or both?
Answer: go for both, remember that the descriptors are different for both benefits, if you kept a copy of your original ESA claim then use that as a template
2) Will it cause problems submitting both?
Answer: No
3) What will happen if she gets ESA and then PIP is later awarded?
Answer: Nothing, ESA and PIP are seperate benefits, some claimants who receive IR ESA can get an additional premium if the receive the daily living component of PIP. (IR ESA is no longer available for new claimants)
You do not have to be receiving PIP mobility component to get a blue badge, but it can help. You can get a doctors supporting letter to help get blue badge for mobility;
www.gov.uk/apply-blue-badge Gary