Customization after member login

I am trying to figure out how to best get our members to the correct landing page after logging in to our Member site or at least make them see the correct content.

What we have done/tried so far:

• Making a "teaser site"  publicly available, so everyone visiting can get a taste of the content on our Member site. 
• After login in, members ended up on the wrong landing page or on this "teaser site" instead of the correct Member site frontpage (it looks the same but doesn't have the red text "login disclaimer" at the top). We then used this code injection to redirect members after login to the correct frontpage.
• That all worked well until now...

New Problem:

• We send out newsletters with links to our Member site, but because they have to login before being able to read the new content, and because of code inject listed above, they now end on the Member site frontpage instead of the site they wanted to see/read. And several people are annoyed but this... 
• I have now removed the code injection so the members land on the correct page linked from the newsletter after logging in. But now they don't land on the Member site frontpage after logging in from anywhere else...

Questions/ideas:

1. Is is possible to manipulate in greater detail which pages members land on after logging in depending on the circumstances? (e.g. "if login in via links land on those linked pages", and "if logging in from our websites homepage, land here instead")
   
   And if that isn't possible or way too complicated, then
    
2. Is it possible to hide a section under certain circumstances?
   – E.g. can I have the "login disclaimer" on the "teaser site" visible when not logged in, but disappear when logged in, so the "login disclaimer" isn't an eyesore and confusing.
3. Any other suggestions on how to solve this smoothly? 🙂

Thanks!