1. Jobroller is a wordpress theme and if you already have an existing wordpress installation, you need to install a separate instance for it either in subdomain or folder.
You can check the available language pack here
JobRoller Language Packs | AppThemes .
2. Dotpay is not yet an option in the payment gateways but you can have it implemented through custom coding as what other users have done.
3. Not a current option but it can be implemented again through custom coding.
4. Yes you can translate it to your language and there is a guide on how to do so.
5. The currency setting is based on paypal supported countries being the current payment gateway.
Since there are no encryped codes in theme you can modify it according to your requirement. Implementation however is just dependent upon your coding skills or you can just avail the services of an experienced programmer. You may also check the Appthemes certified partners here
Certified WordPress Theme Partners | AppThemes .
