Differential vs Incremental Restore and related questions

Hi,

I have read the material for Incremental Backup and Differential Backup.

Incremental
Each increment backup is based on the difference from the last backup (full and increment). On the plus side, each increment backup is small. On the downside, if one increment backup is bad, then all increment backup following it is also bad.

Differential
Each Differential backup is the difference from the full backup. As a result, the Differential file may be larger, but if one differential is bad, the other differential are not affected.

Questions
1. If I restore a incremental backup, and I pick an incremental backup or the full backup, will it get the latest incremental backup in the chain or does retore from the file that I picked. If I have full, inc-a, inc-b, inc-c, and I pick inc-b to retore, it will restore all but inc-c?
2. I assume that differental backup will restore whatever differential I pick?
3. Is increment generally faster than differential due to the smaller file size?

Paul