Well, thanks for absolutely nothing, everyone. Just in case any other noob comes across this issue and finds this thread first like I did, I'll add this to prevent someone from wasting hours of their time with something that had such a simple answer:
Make sure you have the Android SDK software installed on your computer before trying this. I, (being completely new at this) tried sending the commands to the phone by opening a command window and typing the commands straight up; which is why the phone was not responding. Once I installed Android SDK and the Java package, I was able to get both issues fixed in 10 minutes.
Please note that it is MUCH easier to put the two files needed to fix the USB on the memory card (using a card reader) once you have fixed the SD card issue. Fix the SD card first, then download ConnectBot, and put the two files (unzipped!) in your SD card. I followed deviousskater's post on the bottom of page 10 on thread on XDA, which were clearer (for me) to understand, and I got it fixed on the first try. Connectbot instructions are:
su "then press enter on keyboard"
cat /sdcard/flash_image > /data/flash_image "then press enter"
cat /sdcard/mtd0.img > /data/mtd0.img "then press enter"
chmod 755 /data/flash_image "then press enter"
/data/flash_image misc /data/mtd0.img "then press enter"
reboot "then press enter"
(this step did NOT work for me. I just powered down the phone normally by holding the power button, powered it back on normally, and as soon as I plugged it into my pc, it was immediately recognized and began to charge. Make sure to pay attention to all the spaces!)
Now that I have the SDk software installed, I am going to try performing the recovery using this software since I could not get the phone to read the "update.zip" file from the memory card no matter what I tried. While I understand this is for more advance users, I have no choice at this point since I already ran the PC36IMG file to root the phone. I've been at this for a week and have not able to get any customs roms installed yet because I cannot get past the recovery stage.
I hope this is helpful to someone; I know it would have helped me to have seen this and saved me hours of reading and worry.