i've pressed 2 7"s myself (in '98 and '01), and here's what i found:
a) erika records. (98) thicker, sturdier vinyl. a bit more expensive. i had ok/questionable customer service, but the guy i worked with, i think is long gone. this was mastered by john golden.
www.erikarecords.comb) united records. (01) 7-11 of pressing plants and can do it all in one. it was mastered in house. vinyl is flimsier than erikas. it's also cheaper. mastering job not so hot. pretty decent customer service, and had this really nice southern hospitality thing that us northerners fall for really easy.
www.urpressing.com if i were to do it again, i'd go back to erika and have golden master it. hope that helps.
i didn't record either of these, so can't advise mixwise. my guess is if you go with a good mastering engineer, you'll be fine.
-nick