I’m building a 17” FTIR setup, and I recently bought 10 of these LEDs:

940nm Wavelength
45 degree viewing angle to 1/2 intensity
Radiant Power Output @ 100mA: 16mW min
Forward Voltage: 1.2v
Forward Current: 100mA

My acrylic is 14” by 11” and I’m putting these in series with a 100mA PSU and a 10 ohm resistor.

Are they bright enough to put 5 on each side and still get “blobs” when I touch it?

Speaking from experience normal web cams are not as sensitive to 940nm as we would like them to be.  It’s a good idea to drop down a hundred nm or so to something closer to the visible spectrum.

My webcam sees the 940nm IR LEDs more clear than my TV remote’s IR LED. Is this fine? Do I have enough of them?

You will have enough to see some effect… it’s a good experimental start but many people in these forums have found that it is better mount 1 led per inch along the long sides of your plexi… that would 28 in your case.  That’s to achieve maximum brightness without dead areas… you will probably have enough to begin to see how this might work but not enough to build a perfect near zero pressure surface.

From: http://nuigroup.com/wiki/IR_leds/

For now the most preferable infrared leds, that most of the people use, are the Osrams SFH485 or SFH485P. Specifications: 1.5 V 100(mA) 880 (nm) 5mm. The difference beetween the SFH485 and SFH485P is that the first one has a beam angle of 40°. The “P” version has a wider beam angle of 80° and comes with a flat head: