Salam.
I went to Skardu last year and so I will try and answer your questions,
1) Brother from Karachi you should be able to reach Multan in one day but trust me that's a lot of driving. From Multan you can reach Naran and again...you guessed it!! It's a lot of driving... From Karachi to Multan is around 885 km which is around 12-15 hours of driving and Multan to Naran is 775 km which will again take 12-15 hours of driving.
And trust me you would be extremely tired before you even reach your planned destination which is Skardu.
So my suggestion is that you make it 3 days and break your journey at Multan then at Islamabad (540ish km) or Balakot (around 690 kms) and from Balakot to Skardu which is around 440 kms but will take 12 hours keeping in view breaks for sightseeing and pictures etc. Fairy Meadows requires that you park your vehicle at Raikot bridge and then take a jeep to Tattu village (2-3 hr drive). This road is extremely dangerous and not for the faint hearted. From Tattu you can either go on foot or hire mules which will take you to Fairy Meadows and it's another 3-4 hour trek. Fairy Meadows has a range of hotels and camping sites so accomodation isn't much of a problem there. A day trip would be very tiring and you won't be able to appreciate the natural beauty of that place.
2) Balakot, Naran, Skardu has a lot of hotels ranging from low budget to highly expensive ones and so it does not matter much if you don't have pre-booking. Google can help you a lot and you can find contact details as well online. Most good hotels will share room and location pictures on WhatsApp.
3) 4x4 shall be needed for Deosai and Bashoo in Skardu as mentioned by someone else before. You will also need them if you plan to visit Lake Saif ul Malook in Naran.
In Skardu, make sure to rent a Prado for Deosai and the rents will range from 18-25k depending upon which vehicle you go for. Cost of diesal is on top of this. Don't go for the cheaper BJ-40s because you will get back spasms.
You can do glamping in deosai and Bashoo. Very good experience and well worth it. For Bashoo there is a standard jeep service that runs from the banks of River Indus and last year they were charging 5000 for a day trip. We went there for a day trip but then decided to stay the night so our driver charged us 8k.
4) Special instructions: don't stay in Chillas since it's very hot there. Don't stay in Naran rather go to Batakundi or Basel even. Skardu is hot during the day and nights are cool so don't expect to be wearing jackets or warm clothes there. Don't forget to take warm clothes to Deosai because evenings become extremely cold. Don't miss out on Khaplu which is around 3-4 hour drive from Skardu. In Skardu you will love the Sarfaranga desert and the Shigar valley is good as well. Skardu isn't famous for food and cuisine. Do breakfast in Kiwai (between Balakot and Naran) at Ahsania restaurant if you get the chance. It's a nice place and it's a lot of fun to sit on the benches placed on water streams and dip your feet in ice cold water. Don't miss the Sheosar lake in Deosai. UV index shall be very high in most of these places if the sun is out so don't forget to take sun block. Follow Twitter pages of DC Skardu and Chilas to get updates on landsliding and road blaockage.
05815930132 . This is helpline number of GB tourist Police and very helpful for weather updates/zero point closure timing/ land slide information so do use it if needed.
