"The driver is climbing on the bus, and not on the tree."
Translation:A sofőr buszra mászik, nem pedig a fára.
I wouldn't use meg to connect two clauses, but only for listing things. "Almát vegyek, meg tojást meg kenyeret meg tejet..." Wherever you can say "plus" instead of "and" and it still makes sense.
You can, however, use the postposition még if you like: "A sofőr buszra mászik, nem még a fára."
Edit: Whoop, had a brain fart. The postposition is still meg, but it has to come after nem here, just like pedig: "A sofőr buszra mászik, nem meg a fára."
Még means "already".
It's a verb form, yes. The imperative form of vesz - to buy is vegy - "Buy!" or "You should buy." Putting an -ek at the end conjugates it into the first person and means "I should buy".
Szotar.net should find at least venni, though, which is the infinitive form. How disappointing. Also you can try this site to see all (minus two) of the important conjugational forms of Hungarian verbs. :)
szotar.net never finds infinitives. You have to give it the root. But I tried venni anyway, because nothing else was working. Now I know why - "vegy" isn't the root.
I didn't know there was an imperative form in the first person singluar - I know there is in 1st person plural ("let's"). In English, "I should..." isn't imperative, just a guilt trip. :)
Okay, with even Wiktionary and Google not recognising it, I can see how you got lost. Especially since vegy/vegyi is a word referring to chemistry. Point taken. :´)
The Hungarian verbs have imperative forms for all persons, mainly because the imperative mood is used for more than just giving orders. But they can stand on their own to give suggestions, too. You correctly realised that the 1st-person plural imperative is described in English with "let's", so saying "Let's do this" to yourself can be seen as the singular form. :)
Unless the tree is a vehicle, you're going to have problems here. It might work if the tree had a ladder against it, though. Not quite sure.
Also "felszáll a buszra" refers to "getting in the bus", going to use it normally. With "(fel)mászik a buszra" our driver climbs onto the roof.