Contact me from my profile page please.
I like one page templates and with all that jQuery effect I wouldn’t say that it is easier to create them compared to mostly simple inner pages for multipage website.
The most important is that “one page” websites can have more then one page so there shouldn’t be problem with SEO. Single page (the one with top menu and scrolling) can be seen as different layout concept for homepage with preview of content inside sections and link to full content on separated pages.
Design and overall idea are nice but really it needs more polish in terms of typography, hierarchy etc like it has been said.
For example, in my opinion, all headlines have too much space below them like the line-height is not good. Button in slider should have bigger font and be more visible compared to other text. Three columns below slider are somehow not visible enough, probably because smaller size of headlines compared to other headlines below (hierarchy problem) etc…
Another problem for reviewer could be that template is not unique enough so in that case you need to change layout elements order to be more unique.
Gradient in top slider doesn’t fit well in flat style that you want to achieve.
“contact us” doesn’t lead to contact form on the bottom of page but on blog page. I don’t like hover effect with bouncing, the one below “about us” headline. Don’t mix too much different hover effects on one page. Make menu sticky to the top, top slider seems that needs more work.
And most important check space and paddings. That is main reason for template rejection.
Portfolio filter doesn’t work.
Bootstrap because it is most popular framework here. If you want to have full ie8 support then go with Bootststrap2. If ie8 is not much important for you go with Bootstrap 3. It has more complex classes that give more possibility to better optimise layout for smaller devices especially tablets. For clients outside Tf version 2 is still the best choice.