DVD-RW Drive Question

Alright, here's the deal: I'm making my computer in July/August this year, but I'm going to buy a DVD-RW drive possibly on Friday. This computer that I'm on now has a 16x DVD-ROM drive and a 16x CD-RW drive.

A) Will it present a problem if I replace either drive with the DVD burner for a month or two, and then put whatever was there back? What drivers do I need, if any? Do I back up the current ones on my system, and if so, how do I go about doing that?

B) Which should I take out? The 16x DVD-ROM or 16x CD-RW? The DVD-ROM is acting up, takes a very long time to actually push the button and have it come out; instead I need to leave a CD or DVD in there 24/7 in order for it to be obediant and open when I press the button. Should I take that out and have the DVD-RW and CD-RW, or go for the iffy DVD-ROM and DVD-RW? Will my system spazz either time, when being installed and/or removed?

Thanks in advance for information 🙂

Ah well, couldn't edit, but another thing. I'm looking at these two on Bestbuy.com.

Sony: http://www.bestbuy.com/site/olspage.jsp?skuId=6971949&type=product&productCategoryId=cat01041&id=1099387466871
Pioneer: http://www.bestbuy.com/site/olspage.jsp?skuId=6965153&type=product&productCategoryId=cat01041&id=1099385476372

The one thing I'm a bit confused on for these: what's the difference for the " Interface Slot/Connection Port"? Pioneer has "TA/ATAPI-5" listed, while Sony has "EIDE (ATAPI)" listed. Is this a physical difference with the wiring? Does it matter? Am I safe if I buy either of them, or do I need to check connection compatability before I do so? I don't wanna buy the thing and have to return it.