First off welcome to Sunline Owners Club and congrats on your new camper!
I moved your post out to being it's own post here so it does not get buried in the water leak post.
You have a good truck for your camper, do you have a weight distributing hitch and anti sway control for it? If you need help setting it up, we can help.
The water heater, heads up, your model year has both a gas and 120VAC electric element. The 120 VAC electric element can burn out real quick if there is no water in the heater and you turn it on. Once you have water in it, the circuit breaker in the converter panel needs to be on for the heater, then you flip the electric water heater switch on the tank panel and the electric portion will energize. 20 minutes later the water will be hot. That is if all the safeties are working.
The LP gas part you can hear working or not working. When you flip on the LP gas switch on the tank panel, what do you hear or see at the HW heater? The heater when on gas will start by going clunk, (the gas valve just opened) then click click click of the ignighter. If you have no clicks or clunks.... then the tell us that and we can walk you through the process of trouble shooting. The camper battery needs to be on or plugged into 120VAC shore power to run the control board on the heater.
Caulking and the roof.... Being a 2004 your physical roof should not need replacing unless some major use/abuse was subjected to it. May need a good cleaning to get the dirt off and all the sealant around any edge seams and roof penetrations checked and then re-caulked with the correct caulk.
See this post it can help on the roof caulk. Also heads up, the camper roof is not a walk on roof without the help of plywood pieces. This post talks about this too.
Once you get through the roof sealant inspection then yes you can check the front corner edges of the camper for splits in the putty tape like Sarah had on hers.
The trailer has brakes and wheel bearings that need frequent maintenance. If you do not know the last time the wheels were off, the bearings greased or the brakes look at, it would be good to do before a lot of towing starts. Tires, need to check the date codes to make sure they are not the original tires still. 5 years old on ST trailer tires is about it. They may have lots of thread left but an have tread and side wall cracks. Unless heavly used most camper tires do not wear out, they age out.
The fresh water system will need to be sanitized to clean the system before you start camping with the trailer and wanting to use the water system.
Did you get the Sunline manual with it? In there, there is a section about starting up the camper for the season. It will help explain a lot of what to do. If you do not have a manual, in our files section, (tab at the top) there are some manuals you can down load.
Here is a good checklist by Lost Hunter that can help as well
Hope this helps and good luck.
OH and one more thing, go have fun in the Sunline! Most important!