If by yellow you mean a soft white that is ok. Like a regular household bulb that puts off a warmer color. If you have the box the bulb came in, you can post it up for us and we can tell you. It usually tells you the Kelvin rating which is a scale that describes the color of light it puts out.
You want to stay away from bulbs that put out color such as red, blue, purple, etc.
If by yellow you mean a soft white that is ok. Like a regular household bulb that puts off a warmer color. If you have the box the bulb came in, you can post it up for us and we can tell you. It usually tells you the Kelvin rating which is a scale that describes the color of light it puts out.
You want to stay away from bulbs that put out color such as red, blue, purple, etc.
It is really not too big of a deal. Your uvb will be outputting a high kelvin rating of bright white - daylight so the basking bulb kelvin rating isn't a huge deal really. Whatever you can get in that range will work!
The Repti Basking Spot is OK. Especially when combined with a good UVB tube as mentioned. I've used those in the past without issue (aside from perhaps lack of durability).