DIY Shed by a newbie

Hello,

I would like to build a lean-to storage shed next to our house. It will be relatively small, 6'x12', and will be used to store lawn tools, a walk behind lawn mower and other various things that are cluttering up our garage. It will be a basic and bare bones type of structure. I plan on using plans that I've found online and teaching myself as this will be first construction job ever.

This is the plan I will use: [I cannot post links evidently]

My first question is with respect to the foundation and the main issue is that the location I've chosen is on a slope. I've chosen this location because it's out of the way of basically everything and the previous owner of our house had a tent-shelter for storage purposes located there. The tent has been removed and only the frame remains and will be removed when I begin work. Here is a picture of the site: [I cannot post links]. It is a 24'x12' area. The town shed permit form sets forth a 5' sideline setback restriction. I measured to a point 5 feet from my fence (which is approximately on the property line) and then six feet from that spot and using the leveled string and stake method there is a 7 inch variation/slope.

I would like to use gravel/drainage stone and concrete blocks as the foundation. The blocks are 4 inches thick and I should be able to stack them to raise the low side. Is this a good idea?

The plan calls for two 4x4 skids connected to the joists but not on the rim joists (essentially inside the frame and 49" apart). Is it a good idea to connect the 4x4 skids to the rim joists? My lizard brain makes me think this it is the plan doesn't call for it. Might it be because pushing the 4x4s out 6 feet is too far? Alternatively, is adding a third 4x4 in the middle while connecting the the outer skids flush with the rim joists a good idea?

I've never really built anything and I think this will be a good experience. Any advise is appreciated.

Thanks in advance.

Sam