Hi Aranel, I think you can set a different priority for each MX record with the same '10', there'll be no problem with that.
In example:
alt2.aspmx.l.google.com 5
aspmx.l.google.com 1
aspmx2.googlemail.com 2
aspmx3.googlemail.com 3
aspmx4.googlemail.com 6
aspmx5.googlemail.com 10
For the IP number you have, take a look at www.dnswatch.info . It converts your IP number to a valid host name. This is called 'Reverse DNS Lookup'.
(Sorry for my spelling, I speak Spanish
I hope this helps.
Saludos!