What does HMS or SS in front of the ships exactly mean?

There are three main abbreviations used here at SCUSA. Here's what they stand for:
HMAS: His/Her Majesty's Australian Ship
HMS: His/Her Majesty's Ship (Great Britain)
SS: Submarine (also Steamship)
I'm told that RMS, which was used for a few ships, stands for either Royal Mail Schooner or Royal Mail Steamship. However, this appears to be an obsolete title.

Why is the Draco/Ginny ship called Fire & Ice?

It is a combination of their physcial looks, temperments, and after Robert Frost's beautiful poem, Fire and Ice.

Are there any other names for D/G?

Although many ships have different names in different places (i.e. SS Pumpkin Pie at FAP, SS Harmony at Cosforums, SS Aurors at Fanforums, etc), the SS Fire & Ice is pretty much universal throughout fandom. One other name I've found so far is the SS Vemon and Spice over at Acciofirebolt.

Created by Natalie, the concept of having roommates onboard is to make friends and meet new people. All you have to do is request for one, you can specifically ask someone or just request one in general, and voila you'll be placed in a room! Then just get to know your roommate and have fun! *this has since been discontinued for awhile just so you don't get confused why you don't see it anymore*

What exactly is in the newbie pack?

A Mini Jukebox full of assorted D/G songs
1000 cans of Cheese Whiz (yes, trust us, you DO need that much)
Plushee!Draco and Plushee!Ginny (your choice from our selection)
3 Plushee!PHBs
Lifetime supply of glittery mascara
Lifetime supply of bottles of Nailpolish: red with silver sparkles or green with gold sparkles
A complete set of "D/G and the Muggle Appliance Series" Comic Books
Never ending supply of Mai Tais and Coffee
All you can suck, Draco Flavored Lollies
A free ad to advertise for roommates
One picture strip from our very own photobooth
The Official F & I Bible, full of D/G Classics and brilliant one-shots
One pint of French Vanilla ice cream with pepper on top
Free red and blonde highlights
One plushee!Ferret attached to the lips to a plushee!Weasel
One copy of Muggle's Guide to Wizarding Music

What is a PHB?

PHB stands for Pink Haired Baby. This a combination of Ginny's fiery red hair and Draco's white blonde's. Haha yes we realize that pink hair is not possible, but it's fun to think about!

Who are Danica and Caius?

Caius: the male PHB, was named after Justine's PHB in the sims!D/G and the shippers unanomiously agreed that it was the perfect name for D/G's son because it's strong, simple, unique, and not too flowery.
Danica: The female PHB. First appeared in one of XX's skits, whose question was "What would be everyone's reaction if Ginny picked a horrible name for the PHB?". After Draco being horrified at Ginny's name, he suggests Danica instead, which can also be a female version of the name Draco, and Ginny happily accepts.

Look here for more info: FAP Dictionary