TPS61085: Load / Input disconnect when disabled

Dear All
I'm using the TPS61085 to step up battery voltage (between 3,5 and 5V) to 12V.
The regulator works fine, but when disabled, I can see the output voltage equals the input voltage.
I understand this is due to the internal switch that continues passing the input to the output.
Unfortunately this results in 22mA power consumption from battery in my design, when the regulator is disabled.
I understand I have to add a transistor as a switch to disconnect the load.

Questions :

1) Would it be better to disconnect the load or input ? in other words, should I follow the load disconnection schematics available in the datasheet page 16, or should I disconnect the input so I'm sure the TPS61085 sees no input voltage and then consumes nothing ?

2) In the datasheet page 16, schematics mentions 12V/300mA output and the BC857C is rated for 100mA, is this transistor matching the 300mA output current ?

Thanks
Jerome