Loading new data into infocube

Hi everyone,

senario: I have finished loading datasource 0FI_AR_4 in ECC into info cube 0FIAR_C03. Now i am trying to load new data into infocube, i have read some documents about this Process, but i am newbie with BI therefore i don't understand some thing and need to ask:

1. According to this Discussion:

0FI_AP_4 delta issue

we don't have to lock or unlock Tcode, but according to this Video:

SAP BI DIRECT DELTA - YouTube 

minute: 7:09 we have to unlock t-code (for example to create new record). so i wondering if we need to lock and unlock t-code during delta load or not?

2. what is difference betwen Full/Delta load setting in Infopackage and DTP?

3. i have read Referenzs about creating Process chain, incase i create 2 Infopackages: one delta init and one for the delta load. which one should i use in Process chain?

Thanks