Food & camping gas
There is no need to send packages before you go unles you need special food/diet etc. The cost of sending will be much higher than buying along the way plus you support the local shops.
Besides, and from my own experience, you must take in consideration the waste of time it will take to fetch packages/wait for people to get it for you. Some places will even charge you for handling it.
Besides #2: even when you sat at home and counted on what you eventually would need it´s not sure that will be the case once you end up in the mountains.
There will be “real” shops along the way – exept between Kvikkjokk and Abisko and Abisko – Treriksröset. From Kvikkjokk Via Suecia follows the Padjelanta Trail where there are STF and BDL (Badjelannda Laponia Turism) huts along the way. You can buy food in these huts and thus support these organisations. Please remember to bring cash.