@ShoppingBasket - lots of questions here, will answer as best as I can
Why do women shave their heads and then wear wigs?
Married women are meant to keep their "true beauty" for their husbands - now beauty is not meant in the same sense as the modern world but more about their more innate self. Therefore as part of that there are parts of themselves they keep private including their natural hair. However, most places don't have an objection to wearing a lovely wig - it's not about making yourself uglier it's about keeping some parts of yourself hidden for just yourself and your husband. Similar to how your clothes keep certain parts of you private but can be used to make you more attractive.
The shaving this is often done for practicality reasons mainly - it's hot under those wigs and also to help it sit better. there are some Hasidic sects that do insist on shaving but it's more to do with everyone does it than a real religious reason or it may be there's less risk of it falling out from underneath the wig. Some women will chose not wear a wig and instead wear a headscarf or less religious women may chose to just cover their hair with a hat.
Why do men carry plastic bags - why not normal bags/rucksacks or is this just in the tv show? Yeah I noticed that to and I honestly have no idea. there's no religious reason for it - may have just been they were on hand.
They also showed them with white rope around their arms when praying, what is this?
The white strings you may have also seen hanging from their waists and they are tassels of a Tzittzit which is a four cornered garment with strings, knots and tassels which is commanded for a man to wear in the Torah at all times - it is supposed to be a constant reminder of G-d and the knots and tassels somehow represent the 613 commandments in the Torah.
You may have also seen them wrap black leather straps with boxes attached around their arms and heads. These are not bondage gear, these are called Tefillin and the boxes contain certain prayers and they are meant to help men feel more centred and focused when praying.
If a couple end up not have children does anything happen? Do they divorce etc. In unorthodox there was huge pressure to conceive but sometimes it can take couples years through no fault of their own. Is there a pressure there in real life?
There is a huge pressure to conceive in orthodox community as one of the first commandments is to be fruitful and multiple and should someone be infertile their family may encourage them to divorce. However, whilst divorce is allowed in Judaism it is highly discouraged and a Rabbi would encourage them to follow every avenue first including getting medical support if needed. I don't think it would be a case of a year and let's get divorced. However, should a woman be completely infertile then I think in a community like that the man would probably be encouraged to divorce and fulfil the commandment with someone else but only once every other option was explored. I think in this case it was more the family not being particularly fond of her pushing for it anyway.
I know unorthodox has some discrepancies but is it fairly accurate? Or stereotypical?
From what I understand it is fairly stereotypical but there has been a lot of criticism that it focuses entirely on the negative with nothing mentioned of the positive of being in such a community and obviously things are dramatized.