Lexapro is an SSRI, and SSRIs are the standard fist line of treatment for depression & anxiety today. If somebody goes to an MD complaining of depression or anxiety they have a 99% chance of getting an SSRI. Other SSRIs include Celexa (Lexapro is an isomer of Celexa), Paxil, Zoloft, Prozac, Luvox, and I think there's one other. Sexual side effects are quite common with SSRIs and these effects can include the inability to orgasm or loss of libido. As for taking it at night, it isn't likely to matter what you take an SSRI. The standard schedule is take it in the morning if you find it stimulating and take it at night if you find it sedating and if you find it neutral then flip a coin to decide when. If an SSRI works it will likely take 4 weeks and possibly longer for full effect. Studies done by the drug companies (which have strong financial incentive to be wildly optimistic) report that about 70% of patients improve on an SSRI. One should note that these same studies show that about 35% improve while taking placebo, so there is a huge placebo effect here. These studies claim to be "double-blind" meaning neither the patient nor the researcher knows if they are getting the drug or placebo. This is 100% total bull shit though, since it's blatantly obvious to everyone involved if they are getting a real drug or a sugar pill. At least it's obvious to me when the mystery pill makes me totally unable to orgasm. That effect is anything but subtle and makes the study anything but blind! Drug makers know the sexual problems and they intentionally avoid asking about sexuality in their trials. Instead they ask absolutely asinine questions such as if the pill makes you fart -- participate in a clinical trial if you don't believe me on that.
Adderall XR is a perfectly fine choice. I prefer immediate release myself, but lots of folks like the XR version. It's a matter of personal preference.
Wellbutrin: that's an atypical antidepressant, meaning it's one-of-a-kind that doesn't fit into a class with any other drugs. The major selling point of Wellbutrin is that it's one of the very few antidepressants that lacks sexual side effects. In fact, Wellbutrin is sometimes even used with SSRIs in an attempt to counteract the sexual side effects of SSRIs. I really have no idea if that's effective or not. The negative of Wellbutrin is that some people find it too stimulating and it may cause insomnia. At least that's what I hear. I personally didn't find that to be true. It's also possible that Wellbutrin may result in a trivial amount of weight loss. In fact, Wellbutrin tried to get FDA approval to market itself as a weight loss aid, but the FDA rejected their application as they felt the amount of weight loss was trivial. This too could be a significant selling point given that there are people who complain that SSRIs (and TCAs and MAOIs) cause weight gain. I did notice a minor drop in appetite while on Wellbutrin though it wasn't enough to lower my weight. This same drug is also marketed under the name Zyban as a smoking cessation aid. Seizures are a possible side effect of Wellbutrin, and back in the 1980s it was removed from the market due to seizures. That was back when the max recommended dose was 600 mg/day. It soon came back to market with a new lower max dose of 450 mg/day. I knew a woman who was very happy with her Wellbutrin -- at 450 mg -- though she had a number of seizures over a period of years due to it, but she still felt it was worth it.