*Disclaimer* I work for Intel, so i'm a little biased. lol
But, Lets try to answer your questions.
1)There isn't a compatibility issue with Macs, there is usually a linux version of everything and even better you can download windows on your Mac if thats what you prefer.
2 & 3) If you are going to go with the Mac, you should definitely update to the Macbook Pro Model 15' to get the i5 processor. The 13' comes with our older Intel Core 2 Duo. Since you plan on having your laptop a while, you definitely want the newer process so it can handle your egineering software and continously increasing new technologies such as youtube videos, etc. (Plug Warning) We have a new line of Intel Core processors i3, i5 and i7, that are "not just faster, smarter." The i3 is great, but the i5 has Intel Turbo Boost Technology which adapats to whatever your doing, i.e. speeding up when you need more processing power. (Eliminating the irrating freezing and slow responsiveness) The i7 is even better, but since you are not a gamer you may not need that much processing power, but definitely check it out.
4) Again you can purchase windows for both platforms, so I think you should choose which laptop you feel more comfortable with and represents you. From a price standpoint the HP Envy 14 starts at $1,099 (i3, but you can updgrade to i5 for $75-175), while the Macbook Pro 15' (i5) starts at $1799. For $1,474.99 you can customize your HP to an (i5), receive 2 batteries (One 8 Cell Lithium Ion +One 6-Cell Extended-Life Lithium-Ion Polymer Battery) over 11 hours of power, and still save a few bucks. You get 8 hours of battery life on the Macbook Pro 15.' In my opinion you are paying for a more detailed design/ quality of the physical computer and user experience. Macs also very good at protecting against viruses, something you will appreciate on a college campus. It really just depends on what you want to spend and whats important to you.
5) I think the question, which one lasts longer is a ambigious. Apple and HP will both stand by and guarantee their computers. However, I think the most important thing is investing in a strong processor. You can always replace a battery, or fix a screen, but you want your processor to be just as strong today, in three years when you are up all night running engineering software preparing for finals and design days.
Hope this helps, good luck!!