GK - Could have been Trapp this summer or it could be Leno, Karius, Lecomte or someone else next summer. Lloris seems the best option there and I'm not his biggest fan.
CB - Do you think Stones is an improvement on what we currently have and could we offer him enough time to develop as much as needs? Furthermore he'd probably compete with Smalling, Jones and McNair for the right spot and I think we need someone for the left spot alongside Smalling more. Personally I couldn't care less which foot a centre-half uses and would just play our best players, but I don't see Stones and Smalling playing together under van Gaal if the former signs.
#10 - IMO a problem we didn't need to have, but like you said, both Mata and Herrera aren't preferred or fancied there. Rooney, Januzaj and Fellaini seem to be other options. Considering how van Gaal prefers to have a second striker than an attacking midfielder there, Fekir seems to be the best option as he's capable of both and is used to playing just behind Lacazette. Reus, Müller and de Bruyne don't seem realistic at this moment of time. I think it would be easier to improve our wide options and I also think it's needed more with Memphis, Mata, Young, Januzaj and Pereira as options, which is why Pedro probably makes sense.
Striker - I don't think we will be able to solve this one this summer and have to be patient until next year.