temp wise, its made to throttle before temps get high enough to actually cause damage. Long term, sustained high temps and throttling will bring down component lifespan yes, but will you notice before you'd upgrade your laptop, probably not. No one can no for sure, but theoretically laptops were made with this in mind, especially the stealths.
Battery life, well while rendeirng or anything very demanding, you'll get very minimal, so make sure you bring your charger with you. Long term battery, well the more you use it, drain it, charge it, keep it plugged in, the lower the life. Typically they used ot be about 2 year lifespan. Since then batteries have gotten better, but no one knows for certain. You should expect at least 2 years from a single battery, if not way more. Your battery life will slowly get smaller and smaller after that time. But ive had an asus for 2 years i used all the time, and then 2 more years after that used seldmoly, if i run hw info which tries to get a an average battery life %, by taking maximum new charge value, then takes what maximum value you can charge now, and gets you a %. My 4 year old laptops sitting at 93% battery life remaining. Thats pretty darn good. All batteries are not made equal, and usage also comes into play. But you can almost always buy replacements and they normally run anywhere form $30 to $150.