Yes. Most issues have two general ways to look at it. That's how political parties, which Washington and Adams so vehemently opposed, formed. Politicians found that generally "these guys said one thing, and these guys said the other," so parties almost naturally formed. Don't forget also, back in the old days, state and local politics were more important than national politics. People from Virginia were generally one generation removed from wealthy British landowners while Massachusetts folk were here 100 years or more here already and were outcasts from Britain. They could barely hold the Union together at that point. National political parties made it easier to advertise a political platform. The same holds true for state and local politics now. Be honest - when you vote now, how much research do you do on the Superior Court judges running for office in your district? Your state legislators? Even the nat'l senators? At least a Dem or Rep next to their name lets you know generally what they stand for.
The primary process is an opportunity to vote for the candidate that most aligns with your beliefs. Ron Paul and Mitt Romney were both GOP in 2012, but had decidedly different platforms within the party. Allowing people to vote in runoffs is an interesting system that works in some local and state systems, but I'm not sure how it would fly on the national stage.
This is true. I don't do too much research on the middle level stuff (national congressmen and senators, and state senators and assemblymen) yet I still vote for them. And, unless I have learned something about them, I will just pick the Dem for the exact reasons you stated; I generally know where they fall on the bigger issues. Lower level stuff, if I don't know anything about anybody in particular, I simply don't vote at all.
Party affiliation or not, the guy or gal with most exposure (i.e. the most money) is still the one with the best chance, no?
All in all though, I would think less, blind, party-line voting would be a good thing.