SAMBA问题]文件无法写入及多组权限设置

新近在玩SAMBA配置文件共享服务器，碰到下面这些问题
希望大家能给些提示
先谢了。

Samba config file文件内容：
# Samba config file created using SWAT
# Date: 2006/07/06 17:43:10
# Global parameters
[global]
workgroup = workgroup
netbios name = file
server string = Samba Server
browseable = no
log file = /var/log/samba/log%m
max log size = 50
security = user
cat /etc/passwd|mksmbpasswd.sh > /etc/smbpasswd Encrypt password = yes
Smb password file = /etc/smbpasswd
map to guest = Never
socket options = TCP_NODELAY
dns proxy = no
host allow = 192.168.0. 127.0.0.1
[homes]
comment = Home Directories
create mode = 777
directory mode = 777
writeable = yes
browseable = no
share mode = yes
public = yes
read only = no
[share]
path = /home/share
browseable = yes
share mode = yes
public = yes
read only = no
[Marketing Dept]
path = /home/marketing
valid users = @market,@develop
read only = no
writeable = yes
browseable = yes
share mode = yes
public = yes
======================================================
问题1：
market组下的一个用户，比如test用户在共享目录下创建了一个文件test.xls
发现其他用户无法写入，只能查看，查看该文件属性是-rwxr--r--(744)
要求是其他用户能改能删，请问如何实现？
问题2：
[Marketing Dept]目录下想新加一组用户@finance
要求该组用户只能察看marketing目录下的文件，无法修改，如何实现？
目前我把写权限开放给@market组和@develop开放文件使用的命令是
# chmod 777 /home/marketing -R，这样不知道怎么在加一个只读组了
请大家指点，谢谢！。