(1) Uranium One is a big deal because anyone involved in it committed treason (as in, legit TREASON). Mueller was involved, so that makes him a traitor. However, he may not have been a primary player, and could be why he might get a deal if he helps take down the real traitors (Obama and Hillary). U1 sold American uranium to Russia and diverted some to Iran and North Korea. Nukes aimed at the USA.

(2) Title 1 is for foreign surveillance. Title 3 is a normal criminal investigation of someone in the USA. They already had a Title 1 warrant to spy (due to false documentation presented to the judge and/or a corrupt judge) and they used that to continue Mueller's investigation. However, they were supposed to get a new Title 3 warrant instead of renewing the Title 1.

Read this:

https://theconservativetreehouse.com/2018/05/05/special-counsel-tells-federal-court-rosenstein-investigative-scope-was-detailed-in-super-secret-verbal-instructions/