Hi, I have been using dnn for a little over a year now. I have learned everything on my own, and I am always learning new things. The forums can be very helpful if you have any questions.
1) It is very easy to apply a different skin on the website. If you know html and the different dnn tags it isn't that hard to customize a skin you purchase. Every skin that we purchase I have modified to make it exactly how we need it, by adding or combining panes, aligning text in cells, moving or taking out dnn tags, etc...We usually use the www.UCanUse.com registration module. It is very flexible, we can add new fields, and take some of the fields out, make them required, have users added to roles based on fields...It isn't that hard to set up. I don't think that you can edit much of the default registration form.
2) Usually when we upgrade, we contact the company we purchased the modules from to make sure they will be compatitble in the version we want to upgrade to. We always do a complete backup on our files and database before we upgrade, just incase we need to go back. Usually if you just do a small upgrade it will work, but if you jump from dnn version 2 to 4 alot of the modules probably won't work. And, it depends on the asp framework you are running, if you change from 1.0 to 2.0 some of the modules probably won't work.
3) Yes, it isn't recommended to change the core framework. If you add new security roles, change skins / themes that isn't changing the core framework.
I recommend installing dnn and having a test site to play with so you can check out all of the module and see how they work, along with the admin and host tab so you can see what you can do before you start a site. Good Luck!
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Stephanie
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