Yes and yes.
You can use пойдут even if they are driving. Here it has the meaning of attend. Ребенок ходит в школу even if he is actually going by bus (and perhaps even having online lessons).
Perfect aspect is fine. If you use будут ходить it will mean repeatedly or periodically.
Они пойдут на концерт? is a pretty correct, idiomatic, and acceptable sentence.
The choice of the verb in the pair пойти — поехать depends on context.
If it goes about a concert hall where audience enters it walking on foot and the question is about potential visitors, then the default verb is пойти, while поехать will be used only if ‘they’ live so far away ...