A very quick/basic DNS question I need verification on!

First off, I know this is lengthy, but it will be easy for you I swear, and you will be doing me such a huge favor and such a burden off my shoulders if you answer this question. I'm executing a big infrastructure change this weekend and I'm stressed to the max.

1. I'm 99% sure I already know the answer to this, but I wanted to verify with the pros.
2. The main DNS entry I get to play with at my company is a sub-domain of our main site. Lets call my DNS entry, remote.site.com.
3. Our MX records point to McAfee SaaS.
4. McAfee SaaS points to my server, just by IP address.
5. My users laptops and mobile phones are configured using the remote.site.com, which resolves to my server.
6. I'm doing a bunch of switching around with the infrastructure.
7. It will be easy to configure my MX when I move my mail server, because I can just go into the SaaS and change the relay IP.
8. What I'm worried about is changing the remote.site.com.
9. I called last night and they asked which records exactly I wanted to change. I thought back to school, and pointer records, mx records and A records etc. I froze because I couldn't remember.....so embarrassing. It seems that I always learn this stuff once and then forget it when I don't need it anymore.
10. The parent domain, site.com needs to remain unchanged.
11. All of the mx records to remained unchanged.
12. How exactly should I requested to have remote.site.com point to my new IP?
13. Should I say, please change remote.site.com's pointer record to this ip?
14. Or, please change remote.site.com's A record to this IP?
15. Or, please change remote.site.com's A and pointer record to this IP?
16. Or am I completely off base? Knowing what I mentioned above, what exactly should I be requesting? Keep in mind they only thing we use remote.site.com for is rdp, rpc/http and mobile phones. RDP doesn't matter, I'm the only one that every uses it. But the rpc and mobile phone configs... I could honestly be out of a job is I mess that up. The execs where I work LOSE IT when there is any down time, even late in the even on a holiday weekend!