Please Help: How Many Questions On A LIKERT Scale Questionnaire

Im currently doing my M focusing on Learning Transfer. My research instrument will be a Likert scale questionnaire.
My question is:
1) How many questions OR statements should I have for it to be on parr and for the info to be reliable, valid and generalisable? 20; 50; 100????
Also
2) Any samples of questionnaires on Learning Transfer out there that I can use as guides.
Your support is appreciated.

I think I over simplified my comments. Im busy with my MBA and currently developing a Likert scale questionnaire as the instrument to collect data. The main emphasis of my research focus on "Barriers to Learning Transfer". My question therefore relates to the length of the questionnaire. Im using a 6 scales instead of 5 basically to avoid the tendency of selecting the mid point e.g. 1 2 (3) 4 5. Will a questionnaire be suffecient with 20, 30 well constructed questions or statements?

I guessed you would be a student. You have not answered all my questions. Did you read and digest the material in the link I posted?

Yes Im a student and far from being an xpert. I'm currently still reading it and need to do it 1 more time to fully grasp all.

Basically they aim is to investigate the perceptions trainees have regarding supervisor support before-during-& after training, how this support contributes to the achievement of the transfer of learning and also the indirect contribution of this supervisor support on other IV e.g. motivation to learn etc. Broad & Newstrom identified this support as 1 of the facilitators to the transfer process.

Basically other than the perception of trainees, what constitute supervisor support etc.

The objective can thus be: Investigating the variables which constitute theories of learning transfer and synthesising them into a typical common understanding which depicts the most effective methodology for the transfer of learning within organisations.

So!!! From a lay perspective, I need to construct a likert scale with 6 scales from " Strongly Agree" to "Strongly Disagree" to try and get to the bottom of this perceptions and realities regarding supervisor support for training. Hence I wanted to know in terms of the number of questions/ statements that will more or less be exaustive of the topic and at the same time not be to long for the respondent to loose interest. Samples on the topic if any will dearly be appreciated.

Dear Sir
I have read the document and must admit that it is quite informative and very very useful. It will surely come in handy.