problem with contact module after Hikashop 4.2.2 update

Hi,

That's because your template has an old view override of the contact form.
Go in the folder templates/YOUR_TEMPLATE/html/com_hikashop/product/ via FTP and rename the file "contact.php".
That should fix the problem.

Hi,

1. It depends what you mean by "perfectly compatible".
If you mean "a template that won't cause any issue, even if it is updated by its developers in the future, while I update my HikaShop", then, you need to use a template which isn't listed in our list of templates optimized for HikaShop ( www.hikashop.com/download/templates-for-hikashop.html ) as only templates that don't have any customization for the content displayed by HikaShop can be guaranteed to not have any issue with HikaShop updates in the future.
The more a template customizes HikaShop, and the more it risks having something breaking when we change things in HikaShop years down the road, especially if the customization isn't made properly (and that's often the case :/ ).
Now HikaShop will work with any Joomla template, and you can find thousands on them online which aren't optimized with HikaShop and thus which will be "perfectly compatible", if what you mean is what I think you mean.

2. By default ? No.
But if someone work on that for you to implement that capability then it's possible.
Such "product builder" mechanism is usually custom implemented in ecommerce solutions as usually different merchants need different kind of builder mechanism.