Indecent assault is indeed an indictable offense in the United Kingdom. Indictable offenses in the UK are equivalent to a felony charge in the US.

Yes

yes

Some very minor charges are only charged as a summary offense and the most serious only can be indictable. Many charges fall in between this spectrum and can be charged either way. All hybrid offenses are considered indictable until the crown attorney decides how they want to prosecute you.

Committing perjury is an indictable offense rather than a summary offense. A person who commits perjury is always in the position to be indicted when involved in a court case.