Remove option to have seperate shipping address

You need to remove _address of your checkout workflow

I must say I a bit lost here. There is no shipping view in your checkout workflow, so it's normal that you don't see it.

Could you do a screenshot of the whole checkout tab configuration so that we can see how you configured your checkout ?

If you don't want the shipping address, you can just not set a weight on your products and not turn on the option "Force shipping regardless of weight" of the configuration. The shipping address interface won't be displayed.
If however you want a shipping methods selection interface you should do the opposite and hide the shipping address div with CSS:
.hikashop_checkout_address_right_part{ display:none;}

Do you have an address selected when pressing next ?

It seems that there is something reseting the address selection and thus cancelling the order finalization.

I see that you don't have the latest version of HikaShop. Could you first update to the latest and then try again ?

If you overwrite the language file, you will loose what you modified in it.
If you're doing a new translation or translating some new strings, you should make sure that you copy your translation before updating the translation file.
However, if you're just doing modifications to an existing translation file so that it suits your use case, you should do the modifications in the override area:
www.hikashop.com/download/languages.html#modify
When you do that in the override area, you don't loose your modifications when you update the translation file.