Hi ! Rupert , January is next door
for your queries , i'll try to answer to the utmost i can ok !
here we go:
1) Rupert january is quite hot and in the evening you will need light clothes ( T-shirts, flower shirts )
2) You got luck as paradis is situated in the le morne peninsula , there are good winds for windsurfing ( good choice for the place )
3)Normally your travel agency will tell you about the paper works. Believe me coming to mauritius isnt tedious * depending which country you come from you wont be into trouble ^^contact your travel agency^^
4)Mosquitos , Yes there are mosquitos and they bite . but the hotels do take care of it and you wont get problem with that ( a little advice is for you to bring some cream *in case* it will be tough for you to search for that in mauritius
5)Sea fishing is great ##see the stats , mauritius has been in the top 5 concerning sea fishing ( big game) .. if you want to fish traditional too , you can find some locals "very interesting"
6)Car hiring is interesting as then you can discover the island by yourself .avoiding group tours with 15 other people, Attention! dont forget your international driving license!
There are so many places which are worth discovering Rupert believe me * you can have my word on this * Hiring a suzuki samourai can cost abotu 1000 MUR per day but its worth instead of pay 1500 MUR per day for a small excursion.
That was mine help , if you need anything else
feel free & lets wait for other comments