i had already found solutions to apps that constantly keeps on stopping when installed (the one with the case where a textbox "Unfortunately your app stopped working" appears). it turns out i just had to clear its cache and restart the device. which leaves me with just the case with the screenshot above and the case with this other error appears "Your game install has made an error. Please delete and reinstall"
the sample apps for the "failure" and "installation" errors are Triple Town and Magic Rush: Heroes respectively. both are playstore apps. though it also appears that installing apk files from outside sources gives the same error so it's useless. this leaves me with the option of force installing the apps, though i need root permission to do so which i havent tried yet
regarding the sdcard, i have a perfectly fine working apps even when i transferred them all to the sdcard. i used a class 10, U1 sdcard which has a fairly high read or write speed. so i really dont think the sdcard issue matters about the case i had posted. the error "FAILURE ... " is persistent even if i used the internal memory anyway