1. UA probably will not price match but there is no harm in asking

2. UA will assign you in E+ if your status permits but you will need the UA PNR
http://www.flyertalk.com/forum/unite...codeshare.html
http://www.flyertalk.com/forum/unite...codeshare.html
http://www.flyertalk.com/forum/unite...booked-us.html

3.united.com shows the RDM/EQM earning of all partners
www.united.com > Mileage Plus > Earn miles > Partner guide > Airlines > Aer Lingus
Only the IAD-MAD flights earn EQMs or elite bonuses
But remember it is the operator / metal that determines the bonuses -- if it is UA metal AI codeshare, it will be UA rules