Ok, true there were only the possibility of 2 carriers been sunk at Hawii, But it is a what if so lets stick with the 5 carriers of this topic.

Midway - Yes it had a powerful air group, But didnt it take a masive beating in the opening Japanese air strike on the Island, So that air group wouldnt help at all, The planes were destroyed or damaged on the ground, and the yanks got real busy running around removing bombs and munitions to prevent secondary explosions. The Japanese invasion force my take severe infantry casualties (MAY) but they still had to do there shore bombardment, who knows what effect that could have on the defending Infantry.

Simply, The Americans could not hold midway with out here carriers, The Japanese force simply would have over powered them.

Guadacanal - Ok, If the Americans destroyed the Japanese carriers at Midway then of course the Americans would win at Guadacanal, How ever, In this scenario the Japanese carriers were not able to be destroyed and as such would have been able to provide a security force until the air field was built up aswell as the Island defences.

Simply, Carriers provide defence until Guadacanal fully operational, Nothing the yanks can do about it any time soon.

As for the Americans being able to put damaged or sunked carriers back into use, Possibly depending on there condiction, How ever, A ship, flooded, Hit numerous times by bombs and torpedos, As well as being flooded, Would take a long time to put back into action.
First they have to be refloated, then they have to basically rip the gutts out of them becouse its all been stuffed by water, As well as new flight decks, crew replacements and hull repair, This all assuming it structerly sound would take upto a year to complete, Minimum of 8 months. they would not make it to Midway And would be lucky to even have the possibilty of making Guadacanal.