The quality of this bike is beyond your normal bike I would say it would hold a child up to around 50lbs. It says to age 5 and I totally agree with that.

I'd keep checking back, but ToysRUs has it in red but it's more expensive. It may just be in high demand right now, so I'd hold out if you can for the Walmart price.

I'm not sure what you mean by handlebar, since it comes with handlebars. If you mean a push bar for parents, it may be possible but it would have to be custom made. I don't know of any that would fit this trike. My daughter is not quite 11 months old and she can ride on it by pushing it around with her feet (she can't reach the pedals yet, so we will get pedal blocks for her soon - we just got the trike a few days ago). I do have to say that it is made better than all the other trikes out there, and is less likely to tip over.

to answer your question: the site states this is for ages 3-6, but when I received it, the box states ages 1 1/2 -4. and for child up to 38 inches.