With the Free to Play version, are players able to still group up with friends / other players?

One of my friends will be joining the game tommorow, but won't be able to buy the game for awhile. And got me wondering if he'll still be able to join a group with me so I can help him out with some things. I was also preparing a few items to get him started like a bunch of bags with 16 slots. Will I even be able to trade those to him? Since one of the restrictions I read up on for free players is "Can't recieve mail"

They can receive mail with items or gold. They can’t send out mail with items/gold. They’ll be able to group up with you.

In-game mail limited to mutual friends; prohibits sending coin and items, but they can both be received.

This wiki article should answer most of your questions. https://wiki.guildwars2.com/wiki/Account#Free_accounts