Both versions are correct. (source: the language council, and many others). The version written together is actually more frequent if you look at corpora.

Bra is more frequently used. God/gott is used for greetings, to describe tasty food (maten var god), and to describe someone who is really righteous. There may be others I'm not thinking about at the moment.

Good question. I have never heard or said it with the "g". My guess is it gets drowned out in normal speech.

You're right! Morrow and morgon come from the same Germanic root! In fact, morning also cones from the same root. In many Germanic languages morrow is used to mean both "tomorrow" and "morning" but English took "morn" and pattern matched it to "evening" to mean "morning" and began using "tomorrow" to mean the next day, much as Swedish uses "imorgon". For comparison: English - good morning Swedish - god morgon German - gut(en) Morgen [g pronounced]

English - I'll come tomorrow Swedish - Jag kommer imorgon German - Ich komme morgen

All very similar. Cool, no?

You can write valkommen and it will be marked as a typo but you will get away with it. I doubt vaelkommen would work but you can try it and report back. :)

I was wondering the same thing. Seems like the former is more for acknowledging thanks and the latter more for welcoming someone e.g. on arrival? Can anyone confirm if that is right?

"Välkomna" is pluralis, so it should be marked as correct since the English translation could be either.

"Välkommen" is said to one person, "Välkomna" is plural, said to more than one person, If you are talking about something, a noun in neuter (det), that you have longed for and now have reached you, it is now "välkommet", you might exclaim: "Det var ett välkommet förslag!" (look at the spelling: -mm- (between vowels), but only one M before N -mna = plural)