Re: lighting…I looked at fancy lighting and did use larger, pricey fixtures in my indoor, but ended up putting in traditional ceramic single bulb holders in the barn part and buying 10,000 L indoor/outdoor bulbs for them. Super light, but they were like $35/bulb and are easily replaceable if broken. One would be plenty for a grooming stall.
You want good light, but also not to blind yourself so keep that in mind. I think 4 bright lights in that size space would trigger my migraines!