What's your video card? Try updating your DirectX runtimes.
You can try adjusting the "draw distance" option in GTASA's settings. Does it happen in single player?
Add an exception for mta_full_installer_repack.exe and MTAClient.exe in your antivirus program. There is no virus or malware, MTAClient is being detected as a false positive primarily because of its mediocre anti-cheat system.
If you want to play ingame, you must have the client, not MS Paint.
If by "it's only a reader" you mean it's just the runtime files required to run applications, then yes. It's not a complete development package/environment/what-have-you.
Yeah, McAfee only thinks it is because of the way it interacts with gta_sa.exe. It's completely safe.
If we were distributing malicious software, do you really think we would be this popular?