The standalone images now have been made available for all AP's in a single file, when you down the image file , you will get the images for all AP's and can use the one you want , this way you have images for all models and do not have to download a an image every time you have a newer model.
We have changed our firmware versions post 9.8, the 9.8 release was the last one to have standalone AP images , from 9.9 onwards there is no standalone images for AP's , all standalone images need to use the 100.x firmware releases. This is also the reason why you do not see standalone images for 9.10.
If you have a standalone AP and want to use the 9.8 version, you can download the 184.108.40.206.14 version which is the latest Maintenance Release , else you can use the 100.1.0..0.94 , which is also meant for standalone AP's.
MIB files are used to upload in a MIB browser to run SNMP traps etc to understand the networks performance and also to troubleshoot issues.
Hope this has answered all your questions.