i have some doubts which i want to ask.
here are some of the general conversational lines which i have either heard or read somewhere...
1) "she beat me to the office." ( I read this in dictionary . shudnt it be beats??)
2) "The light flashes every second." (Is it different from "the light flashes in every 5 secs" or both ara correct?)
3) this is a line from a novel which i didnt understand " When Pandel's conscience was bad he couldn't help himself anymore than Louisa could help rising" ( I dont actually what was the context then. Louisa is Pandel's wife.)
4) Whats the difference between " I had lost my notes and had to ad lib the whole speech ; I lost my notes and had to ad lib the whole speech"
5)what does it mean? " You can do whatever you like, for all I care "

1) 'beat' is fine in that context. It's the past tense of BEAT.
2a) 'in every 5 seconds' should be 'every five seconds'.
2b) 'every second' means, every single second/each second.
3) I'd need more context, sorry.
4) 'had lost' tells us that event happened first, before 'had to ad lib'. The phrase 'had to ad libo' is a modal auxiliary.
5) It means, I don't care what you do.
I would have answered 4) a little differently. In both cases the losing of notes precedes the having to ad lib. In "I had lost my notes ..." the speaker takes a past point of view; In "I lost my notes", he takes a present point of view.

"I had lost my notes" is the past of the past.
"I lost my notes" is the past of the present.

"I had lost my notes" is a flashback to a previous time when telling a story in the past tense.
"I lost my notes" is just another event in a series of events told in a story in the past tense.