All praise be to Allah, and may His peace and blessings be on the last and best prophet and messenger, Muhammad.
The concept of going out to give da’wah is a vitreous and sunni one. Most of their effort is praiseworthy and there is much to learn from their good manners and conduct.
The numbers mentioned here above would be a bid’ah if they try to religiously justify them or give them any religious significance. Unfortunately some of them do.
If these numbers are used – and known to be so – only for organizational convenience, then that would not be bid’ah.
Your observation about neglecting family obligations is shared by many others. This is wrong, especially if you know that ‘Uthman (may Allah be pleased with him) stayed behind and didn’t join the battle of Badr to care for his sick wife.
The wisdom in giving da’wah is variable, some of them are wiser than others and
some are more experienced than others, and that is expected in any large group of their size. It may be however preferable to concentrate your da’wah onto people who share your same language and cultural background, for your da’wah would be more effective. Allah said what means “we have not sent a messenger except one speaking the native language of his people”.
Yet sometimes there would be a need for people to move out to places which lack preachers, such as the case in the former USSR States after gaining their liberty, or certain places in Africa not reached by Muslim preachers. In these cases the Tableegh Jama’at has done work that is praiseworthy and was required of the ummah.
It would also be important for them and all Muslims to pay more attention to the authenticity of reports quoted and knowledge preached.
Their thinking that studying knowledge would divide the people is incorrect as a general statement and permanent position; otherwise ignorance would be bliss, which is untrue.
Their dispraise of the involvement in politics and legitimate Jihad is very concerning as well.
In summary, their basic concept is good and much of their work is beneficial, and there is a lot to learn from their manners, humbleness, etiquettes, organization, cooperation, etc. And we hope that they re-evaluate some of their positions, which they may have adopted in a particular era and place for particular reasons. We also hope that they re-evaluate the distribution of their da’ees and the utilization of resources. And finally, we hope that they utilize more of their time in learning authentic knowledge and learning how to keep learning a positive experience and one that will create more unity.
For you, if you don’t have another group in your area that has a more comprehensive approach to the work of Islam, then I would recommend for you to work with them, particularly if you have a family and kids, you must keep them busy working for Allah, lest they will become busy with other things. You should continue to be critical (wisely) of any wrong doing you observe on them or others.
May Allah guide us all and honor this ummah and bestow his mercy and forgiveness on all of those who intend well for Islam and the Muslims.