Greenhouses, Sheds and Sun Rooms - shed foundation

i'm planning on putting up a 10x12 shed and wanted a couple of opinions on the foundation. i know a slab is the best, but i'm not pouring one. what i plan to do is make a 12x14 frame from pt 2x6's and fill with about 4" of gravel, level with the top of the 2x6's. i would then construct the shed on directly on top of that. i am putting in a floor, so i'm going to use 4x4's to frame that and sink 3ft rebar through the 4x4's to secure it to the ground. any issues i should be concerned about doing it like this?

The only thing that I think about is since the foundation is larger than the shed where will the rain water drain. Also melting snow and ice. If it can drain well I see no problem.

the gravel will help with drainage, from what i've read. i was also thinking about grading the ground under the gravel towards the middle and running a channel down the middle away from the rear of the shed. good or bad?

What do you plan to do when the shed blows away in a big storm (if you have any)? 3' rebars stuck in the ground are worthless when it comes being a hold down.

A big shed can catch a lot of wind and you can only put so many lawmowers in it if you want to get at anything.

I have seen many houses hit by a roaming shed during a storm and we get very few tornados.

Dick

What do you plan to do when the shed blows away in a big storm (if you have any)? 3' rebars stuck in the ground are worthless when it comes being a hold down.

A big shed can catch a lot of wind and you can only put so many lawmowers in it if you want to get at anything.

I have seen many houses hit by a roaming shed during a storm and we get very few tornados.

Dick

maybe a suggestion then?