"To" isn't necessary in this sentence. You can say "help someone do something" or "help someone to do something". --> "He is helping me clean my room" and also "He is helping me to clean my room". They have the same meaning.

It isn't necessary. In this case, we are using 'help' as a causative verb. Causative verbs, such as 'make' and 'let', can be followed by a bare infinitive (without 'to'). 'Help' can be either a causative or a non-causative verb : you can either 'help someone to do' something, or you can 'help someone do' something. There is no difference in meaning.

Yes you need to write "to develop" :)

yeah it's necessary to put 'to' before develop because the first verb is already conjugated, also i think it's butter to write it like that ' he's now helping to develop a technique' ....good luck ;)

Yep , it should be " to develop " . infinitive ( to+Verb ) It is like passive sentence. He's now helped to develop a technique ("by Someone") which is omitted.