1. Line odds are published by sportsbooks and betting exchanges. As an example of line odds, Odds Wizard fetches bwin fixed odds 1-X-2 and double chance odds 1X-2X. It is done by several methods in Odds Wizard. In particular, you can press F2 to view the latest bwin odds. Afterwards, the line odds can be fed into Stake Wizard tool along with the fair odds simply by choosing desired event and type of bet, and pressing <Ctrl-F>.
Handicaps offered by bookies may differ from those calculated by Odds Wizard due to the different handicap bases. To align the bases, you can adjust them manually in the grey editable column 'AHO', and press <Enter>. Corresponding odds for 1 and 2 will be displayed immediately. For example: sportsbook offers AHO (0 : 3/4) 2.00 v 1.60 for Toronto FC vs DC United (April 17) while Odds Wizard has calculated (0 : 1/2) 1.91 v 2.10. Now we enter AHO (0 : 0.75) in the AHO column and press <Enter>: 2.23 v 1.83.
2. Odds Wizard computes fair odds 'on-the-fly' in a second. It does not rely on any external data source. Empty odds table might have another reason, e.g. shareware (unregistered) mode for the big leagues.
3. Yes, but not for a single match. It is better to use new Stake Wizard files for a set of chosen weekend events (Line > Fair). That's right, Z ave 4% limit (= 104% ROI) is recommended to ascertain good success.
Those who are reluctant to bet big amounts, may want to increase the confidence probability level to e.g. 99%. This will result in less amounts of calculated bets.