This chalk line should be level and a consistent distance from the eaves or the top and bottom of the windows.
Seal bottom of vinyl siding.
This would 100 seal up theair leaks and cover all the gaps where critters can get in.
This is where the new siding will begin.
There are 3 main types of siding.
In addition again talking from the vinyl experience the siding is not really the air barrier vinyl often has a drain hole in the bottoms of each layer to allow moisture to escape so sealing it would do little to nothing for your air infiltration.
Mice can climb under the siding and enter the home through an existing construction gap.
Grass and mulch along the foundation provides habitat for mice.
Caulking is not usually the solution to a mouse problem.
You will want to stick your fingers behind the bottom row of siding and run them along the entire perimeter of the home.
Vinyl siding starter strips snap a level chalk line for the first starter strip at the base of the wall no less than 8 inches above ground level after determining the lowest corner of the house.
On the other hand what may help is sealing you sheathing plywood osb to the foundation.
Bottom line is you don t caulk places where water needs to weep out.
6 siding transitions by foundation often siding is not secured all along the bottom near the foundation.
Wood vinyl and aluminum.
Vinyl siding does not fit tight inside j channels or corner posts you don t caulk them shut and there are voids behind the lap siding too.
Although vinyl is impervious to water when installed as directed by the manufacturer vinyl siding as a whole is not completely watertight.
Simply apply this inexpensive filler into the cracks to seal.
The bottom row of siding should sit flush against some form of backing.
If it s 3 4 or more i d concider removing the bottom row of siding and starter strip and install a piece of 1 x 6 vinyl lumber then a piece of z moulding then replace the starter strip with j moulding reinstall the siding.
Each one has its own vulnerabilities.
There are professional materials that can be utilized to secure these areas on a home.