1. On an Obi110 the default is that calls go out on the POTS line. Check the setting of 'PrimaryLine' under Physical Interfaces, Phone Port. If you configure via the Obitalk portal, you'll need to use the Expert Configuration.
or dialling a # will connect you to the landline and you can then dial the desired number.
or preceding a number with **8 will force the call to go via the landline.
2. You cannot. Caller ID is a number and that is what reaches the Called Party's phone service provider. What, if anything, that service provider does with that number to produce a Caller Name to send to the Called Party is entirely up to that provider. Neither you nor your service provider can control that.
(In the case of a call which is entirely VoIP from end to end, transmission of Caller Name may be supported. However, in your case of all outing calls going over your landline that can never apply.)