Sounds like you're mobile, with the setting up and packing up .... so yes, I reckon you can add 10 minutes for setting up and at least 5 for packing up and the client farting about deciding where to sit and where the power point is etc so there's 20 minutes for you lol
If it's a straightforward application rather than removal and new application, 40 mins (been doing it a year) ... add on the above 20 mins, that's an hour, then a bit more cos you're new.... you're not far away really!
re: the lamp ... a Daylight table lamp (the pull up mobile style) is fab for nails, had mine nearly 10 years and still on the first bulb.... it's robust, has a handle, great light which highlights ANY defect which is so useful, and also doesn't strain your eyes no matter how much you use it. Oh, and it doesn't heat up at all so your Shellac/gels won't run and if you do acrylics they won't set before you're ready! Available I think from Ellisons, also places like Hobbycraft.
As for them not lasting, how many Shellacs have you done? Are none of them lasting? I find the stronger the nail, the longer it lasts ie weak and wobbly nail = forget it and do overlays, not bad nails but not that strong = 1.5 - 2 weeks, thick strong nails that don't move when you try to flex the tip slightly HURRAY probably a month or so! What are the clients nails like that you are finding it's not lasting on?