Macbook Pro vs Macbook Pro Retina Display vs iPad air/mini

Hey everone. I believe it may have some discussion around this one, but i still got some questions - and some personal info that my change the answers. And I appreciate a lot if you all here can help me. I really don't know what to do.

By June I will have started a pre sessional english course at a university as a exchange student and then, by september. a undergrad. course - biological sciences. I am already enrolled at a university and in my research I only use simple softwares like BLAST, FASTA , bioestatisc, ANOVA etc. So no overcloking.

I now have a Dell (I7 4gen, 8GB DDR3, 1 TB sata, video: AMD Radeon™ HD 8850M 2GB GDDR5) that I bought this past december. I think i never overclocked it and do not do any gaming havier then the sims 3, WoW and neverwinter.

As an exchange student, I received 1000£ to buy either an tablet or a notebook. And I have to spend this money with it. My first thought was a Mac. I also have 10% off and i think 15%off with NUS extra card and I am willing to use some more money if necessary.

But what is the best? Sell the Dell, keep the Dell?

Buy a new MBP with retina display but no cd/dvd player with an i5? The old one with cd/dvd player and with a i7? Or buy just and iPad and keep the Dell for other stuff?

I am looking for a device that can endure at least 4/5 years and is easy to work on. (i.e web, crimson editor, fasta etcs).. I see iPads like iPhones but biggers... Are they more for entertainment?

And, about the absent of cd/dvd players in macbooks... is that really annoying? (I think the last time I used a cd was a daft punk one to put all the musics in my computer and then to play the sims 3).

Ah, are there any good games (i.e. Resident Evil, Need for speed, call of duty, far cry) for Mac?

thanks guys I'd really appreciate some help.