Just buy the plain CTS2 not the one with attitude of anything like that. Just the cheap ol CTS2 off amazon was 349. Cheaper than you are going to pick up isspros anywhere and it allows you to monitor alot more and clear check engine lights etc etc and help diagnose any problems later on.
The Edge CTS2 is a monitor that plugs into your obd II port and reads your vehicle vitals. The egt probe is an external plug in and allows for reading of those temps.
As far a tuner if you want cheap but still good tuning the best thing you can get for cheap is an off the shelf TS tuner. Doesn't even necessarily have to have custom tunes but companies can rewrite custom tunes onto it later if you want them and it is cheap. .
The positions for it are as follows and since you have a manual you dont have to worry about trans tuning. I have run a DP tuner on my last 3 7.3 trucks which were all auto and this RCSB 7.3 I have now I am just running TS tunes as its a 6 speed and the performance is similar to previous trucks.
1 - Stock
2 - High Idle
3 - 50HP
4 - 75HP
5 - 100HP
6 - 140HP
See if there are vendors here that sell them but this is what im talking about as far as cheap and a good tuner.
http://www.xtremediesel.com/TS-Performance-Switchable-6-Position-Chip-7.3L-Powerstroke.aspx
And as far as maintenance. The 7.3 is a great motor and super reliable.. Keep up on oil changes and fuel filters. The in tank mods I attached a link below they are called the Hutch and harpoon mods.. This is the first truck I have done them on because you have to drop the tank to access the in tank pickup and make some modifications and run an external filter. So worth it IMO as it gets rid of alot of engine cackle, unneeded parts and allows you a changeable external filter.
http://www.guzzle7pt3.com/hutch.php