Neither are quite right. You would try to eat A little more healthILY than you had DONE. Word order in B reads a little easier.

The best online dictionary is here: http://www.nob-ordbok.uio.no/perl/ordbok.cgi?OPP=&bokmaal=+&ordbok=bokmaal It is norwegian to norwegian, but if you use Chrome you can translate the page to make sure you have it ok. It also has all the conjugations of all the words (click on the v next to the word and you get all the tenses). I use Memrise.com to learn vocabulary. I built up my own courses with words I collected at norwegian classes and there are quite a few courses up there to chose from. You are encouraged to associate images (mems) with words to help remember them and then the program tests you repeatedly, more on words you get wrong more often. Its free to use. Others have recommended Anki. All the course textbooks from the classes (På Vei, Stein på Stein, Her på Berget) have online exercises you can try. For instance https://pavei-oppgaver.cappelendamm.no/

It is more natural to put the He before the have: Where might he have gone/gone to at this hour? The word order 'Might have' would generally be shortened to 'might've' and would normally be spoken rather than written, unless a transcription of what was spoken. Its more coloquial.

There is no indefinite article in the first sentence because you are using 'this' (a demonstrative) and so refering to a definite and particular step. The uses of 'a huge step' implies there are other steps also being taken, that this is one of several/more.