Help - brown tip/ stem / what is this white bug (maybe thrips)

The brown tip is often from overfeeding, but think yours might be from heat stress. Being close to the surface of the soil, it probably gets a lot hotter in the 30C sun. Stem looks normal to me, nothing to worry about. The bug in the shot is a whitefly, they are a pain in the ass, but not the worst pest to have. With such a small plant I would advise against spraying any oil on it. If you have the mix too strong or in the sun after spraying, you can often end up doing more damage to your plant than the pest. A light soapy water mix maybe and spray under the leaves, because that's where the eggs of the whitefly will be. Best would be to get predator bugs like ladybugs or lacewings to eat them. Your plant is starting to flower, so I wouldn't spray anything for too long if you do decide to. I would say max 2 weeks to be safe. If possible, try to find a bright, but cooler area for mid day if it's getting a bit hot. I have found most autos don't like being too warm.