What is the total size of 1040STE with 4 of these SIMMs installed?
Should be 4 MiB. The chips shown are MiBit chips (1 Mi x 1). 8 of them give a Mibyte per SIMM. It also fits, as 4 MiB is the default (i.e. without additional tricks) maximum RAM for a 1040ST.
This great page tells about everything you never wanted to know about Atari ST using SIMM.
How to check the memory using software and which one?
While there is an OS function to return the amount of memory installed and used, it is not displayed with the ROM tools. You will either need a dedicated program or an accessory. Above page got as well a section linking examples for both. I would recommend the accessory, as it will be quite helpful to detect memory huggers. Then again, 4 MiB is more than needed by most ST applications, as next to all work with 1 MiB.
4MiB was the maximum that could be installed in the 1040STE. The MMU didn't allow for more.