Best check with the PD for any fees for false alarms. And there may be a town/police fee - and there may be a key needed for the PD to turn off alarm.
Web cams. If you want web cams - then do check on access costs and bandwidth. More expensive is not the best. If you do have web cams - do you plan to store images? Need a hard drive for that.
If you are worried about break-ins spend money on good homeowners insurance.
If you are just worried about attempted break-ins while you are there - then make sure you get a loud alarm on house that is easy for you to turn off.
There is a lot of technology out there. Some work good. Some don't. When you find an installer - go visit a couple of homes that installer has done and talk with owners. Make sure that these are over a year old.
If you really want to learn about alarms go to the EHX trade show in Orlando where all the vendors are.
http://www.ehxweb.com/