1. High mass loss rate AGB star need a large atmosphere. Its photosphere will be around 1.5au. ​Liljegren et al. (2016) use 1.5au AGB and achieved 3\times10^{-6}M_{\odot}/yr. However, 1.5au will be too large for us. The tidal force will be 50% of the gravitational force from the AGB star. The highest mass loss rate I can do is 10^{-7}M_{\odot}/yr. Below is the mass loss rate in 3-D simulation. I sum the mass flux through a 10 AU spherical shell. The luminosity of this AGB star is 2343L_{\odot} and mass is 1M_{\odot}. So the mass loss rate and size is between RGB and super AGB.

2. A detailed description of this AGB star model can be found here ​summary

3. A 3 AU separation simulation now will take about 5 days on 120 cores. I tested the resolution on single AGB star and it has a difference. The size of the simulation zone is 48au^3. The previous resolution is 120^3 base grid with 2 level of AMR. The current AMR is 3 while the base grid resolution is the same. The finest physical resolution is 0.05au thus the AGB star has 18 cells across its radii. The photosphere has 21 cells.

4. I calculate the strength of tidal force by:

(\frac{M_{com}}{(d-r_{AGB})^2}-\frac{M_{com}}{(d+r_{AGB})^2})/\frac{M_{AGB}}{d^2}

where d is the binary separation. Substitute d=3au, r=1.5au, M_{AGB}=M_{\odot} and M_{com}=0.5M_{\odot} you will get the value is close to 0.5 which is 50%.