Eichler window replacements-not the usual questions!

I am in the process of remodeling an Eichler  in San Jose area I just purchased. Right now, window is my number 1 issue. I have read all I the information I could find on the posts and different websites but so far I have not been able to find answers to some of the questions I need to figure out. I appreciate it if anyone has an insight!!!

1-I understand the "Frameless window replacements" have limited waranty. What I have not figured out is how frequently do people run into problems with this option. Is it worth the expense or should I go with a narrow frame now?

2-I understand the major drawback with  the Aluminum frames is their energy inefficieny but how much of  a factor is this in California weather (assuming global warming will not turn here into an oven...)? Would it add up to a significant amount on my monthly bills or I'm better off going with vinyl which I dont like....

3-Other than the trimming required with Milgard's narrow aluminum frame  when compared to Blomberg's custom fit is there any other major difference? I looked at the samples in the show room and honestly the Milgard had a cleaner look, am I missing out on something? I hear Milgard is really good with their customer care later on.... 

4-Finally, if I go with a framelss window and Milgard's aluminum frame  and they are right next to each other, does the post have to be beefed up?

Looking f/w to your responses!

Thanks

Sarah