I personally think concerns (1) and (2) are of issue but concern (3), of feeling you guys can get a better seed investment, shouldn't be a concern.
For concern (1), it's one thing to be generally hard to reach, it's another to not answer calls. Being a cofounder requires an immense amount of reliability, if you're having doubts about his already that could lead to significant trust issues.
Talk to him about it. Approach it in a friendly way. Being confounders, you're going to have to have a lot of these tough conversations. I'd recommend reading the book "Critical conversations" that gives a great number of examples of how to deal with these situations.
http://www.amazon.com/Crucial-Conversations-Talking-Stakes-e...
All the best man, hope things work out.