Mass-effect – ny time limit on Assists

Firstly for an initial point of no return - as soon as you get access to the Sirta vendor in the Hospital ward buy a/the present/s, completing missions removes them quickly before you know their value.

Secondly before beginning Priority: Tuchanka you should finish off as many sidequests as you can, since completing it renders some sidequests as failed. Don't panic about having some remaining in your journal however, a few don't have their locations unlocked for retrieving quest items until later.

Thirdly Priority: Cerberus Headquarters is the point of no return for the rest of the sidequests. You can still use the onboard vendors on the normandy to purchase goods, but because of the price markup on the ship it's better to visit them directly for whatever you need before commencing this mission as well.

The new character James Vega, is voiced by celebrity Freddie Prinze Jr.

It appears that all major voice talent returns except for Mordin Solus, assuming those characters even have a part in your Shepard's story.

Mordin Solus was voiced by Michael Beattie in ME2. I'm not sure who they used to recast in ME3, but the part is not listed on IMDB, despite the character being fully voiced in the game. It has been confirmed to be a different actor though.

The IMDB page listing the cast is located here: http://www.imdb.com/title/tt1839558/fullcredits#cast

Mark Meer voices Mordin in ME3. He was used as a placeholder in expo demos etc whilst they tried to recast Beattie, but they eventually went with Meer.