There are many options for textile medium type moisteners, but some of the more common ones are Liquitex Fabric Medium and Golden Fluid Matte medium. It will stiffen the fabric slightly, but can be used in a 50-50 dilution with water (distilled water if you want to be ultra safe long term).
Be aware that Golden GAC 900 Fabric Medium requires adequate ventilation because it releases low levels of formaldehyde when heat set. For that reason alone, I avoid it even though it has a very soft hand. Their Fluid Matte Medium mentioned above, is not technically a textile medium, but does reportedly work well with Inktense. I have not tried it myself.
Aloe Vera gel (the clear gel only, don't use the green gel and don't use lotion) stiffens fabric and should be used sparingly. I didn't like the results with it so I went to Liquitex Fabric Medium. The medium controls bleeding and gives a nice smooth surface with both Intense Pencils/Blocks and acrylic paints. I get mine at Dick Blick, but you could look locally.
http://www.dickblick.com/products/li...fabric-medium/
Textile mediums as wetting agents are both ironable to heat set and washable, to answer those questions. I don't like using just plain water because it spreads the ink too much, dilutes it, and doesn't protect it from fading over time.
This is an excellent article comparing the different wetting agents and the results obtained from using them. It should answer a lot of your questions.
http://lindasteelequilts.blogspot.co...e-pencils.html