Congratulations on your ham ticket Brett! Very fun hobby all of its own.
I know you are asking specific questions about using your already bought HT, but I tend to agree with Andrew.
HT's are fine for starting out, and can be very useful in times of high lightning. They are very limited in range due to low wattage, and antenna's however. You could spend money on power amps etc, but by the time you do all of this, you could probably buy a new mobile rig for about the same price.
Again, nothing wrong per-se' with the HT, but IMO, it makes better sense to save your money for a good mobile unit and antenna, unless you just prefer having the HT style. You can probably pick up a good used mobile unit for about 100 bucks at a hamvention, or local club sidewalk sale. You can also move a mobile unit from the house to car or vis-versa fairly easily. Since you already have an HT, that might not be necessary.
Whatever you decide, congrats again on your ham license, and welcome to the (ham) hobby!