Hardwall

[fortech]

Hi all, it appears to be me asking all the questions, but better safe than sorry.
O.K, here's a couple for you:

I have left the course for just over a year now and I have now come across hardwall, but how do you apply it. Is it, apply, rule then devil float as in bonding or apply, rule, rubup, devil float as in render. If you do rub up do you use the poly float or a sponge float as I have been told by someone.

After fitting a bellcast bead above the dpc on aerated blocks for external render, what happens to the blocks below the bellcast, do they just stay on show or can they be rendered as well.

Thanks