1) Why not get a larger card? I bought my 32gig class 10 cards for about $20-25 from amazon.
2) If your USB is FAT32 formatted, you can move your sd:/apps directory to usb:/apps and then tell HBC to look in USB for your apps instead of SD by pressing "1" and selecting USB.
3) If you've not set up priiloader to do this, you may be missing other recommended settings in priiloader. Check the "Softmod any wii" guide (link in my signature). But yet, priiloader can be set up to launch an app of your choice on boot (I have mine set to boot to CFG).