Definitely YES!

Use a 301 as soon as possible... this is the only correct way to ensure that your linkjuice is passed to the new URL

"How important are the image height/width attributes and would you expect a best practice site to have them included ?"

This is not the most important SEO thing in the world BUT according to your 2nd question

"I hear not having them can slow down a page load time is that correct ?"

That`s the point! The question related to this issue is how relevant the whole thing might be?

Modern browsers and broadband connections seem to make this insignificant but just in case there are some visitors which are not using the right settings they might get pictures unscaled and your whole site will be shown non-responsive... by the way, use responsive designs if you can to avoid that...

Ive always been told to use these parameters . even if you dont need it it ensures that your code is a little bit more perfect

Officially it is said that the CC of a TLD makes no difference for the ranking if you do your SEO homework right...

I would agree with that in general BUT inofficially the CC of your domain matters in your case - .re is not comparable to  a .com domain! Take a look at the serach results: there are only a very few examples that a .re is ranking on high position outside it`s dedicated country.

If a CCtld spells the name of your project it has no real influence or relevanve for the googlebot... it`s just a nice thing for yourself, marketing and maybe the visitors of your site.

You dont need to buy the .com domain but if you can do so, I would always prefer this solution. This is always a question of money and if its worth it for you.

My opinion is based on long-term experiences.

If you rename your project it`s easy to transfer linkjuice, authority etc. by using a 301 redirection...

take a look at this and keep in mind that this is 2 years old!!!

http://www.webpronews.com/google-duplicate-content-2011-12